Methods of Preparation of an Olefin Oligomerization Catalyst

ABSTRACT

A method of making a catalyst for use in oligomerizing an olefin comprising a chromium-containing compound, a pyrrole-containing compound, a metal alkyl, a halide-containing compound, and optionally a solvent, the method comprising contacting a composition comprising the chromium-containing compound and a composition comprising the metal alkyl, wherein the composition comprising the chromium-containing compound is added to the composition comprising the metal alkyl.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation Application of U.S. patent application Ser. No.11/928,756, filed Oct. 30, 2007 and published as U.S. 2008/0058534 A1which is a Continuation Application of U.S. patent application Ser. No.10/783,737, filed Feb. 20, 2004, now U.S. Pat. No. 7,384,886, bothentitled “Methods of Preparation of an Olefin Oligomerization Catalyst.”This application is also related to U.S. patent application Ser. No.12/057,853 filed Mar. 28, 2008 and published as U.S. 2008/0177122 A1,which is a continuation of Ser. No. 10/783,429 filed Feb. 20, 2004 andpublished as U.S. 2005/0187098 A1; and Ser. No. 12/534,536 filed Aug. 3,2009 and published as U.S. 2009/0292090 A1 which is a continuation ofSer. No. 11/207,232 filed Aug. 19, 2005 and published as U.S.2007/0043181 A1; all entitled “Methods of Preparation of an OlefinOligomerization Catalyst.” Each of the above patent applications ishereby incorporated herein by reference in its entirety for allpurposes.

FIELD OF THE INVENTION

The present invention relates to preparation of catalysts for use in aprocess for producing an olefin oligomer. More particularly, the presentinvention relates to preparing trimerization catalysts comprising achromium-containing compound, a pyrrole-containing compound, a metalalkyl, and a halide-containing compound for use in a process forproducing an alpha-olefin oligomer comprising 1-hexene from ethylene.

BACKGROUND OF THE INVENTION

Olefin oligomerization catalysts are known in the art, but sometimeslack selectivity to a desired product and also have a low product yield.Enhancements in preparation methods for oligomerization catalysts toimprove productivity and selectivity to the desired product can reducecatalyst cost and improve economics.

SUMMARY OF THE INVENTION

Disclosed herein is a method of making a catalyst for use inoligomerizing an olefin comprising a chromium-containing compound, apyrrole-containing compound, a metal alkyl, a halide-containingcompound, and optionally a solvent, the method comprising contacting acomposition comprising the chromium-containing compound and acomposition comprising the metal alkyl, wherein the compositioncomprising the chromium-containing compound is added to the compositioncomprising the metal alkyl.

Further disclosed herein is a method of making a catalyst for use inoligomerizing an olefin comprising a chromium-containing compound, apyrrole-containing compound, a metal alkyl, a halide-containingcompound, and optionally a solvent, the method comprising abatingprecipitate by contacting a nitrogen-containing compound with a metalalkyl prior to contacting the metal alkyl with the chromium-containingcompound, the pyrrole-containing compound, the non-metalhalide-containing compound, the solvent, or combinations thereof.

Further disclosed herein is a method of making a catalyst for use inoligomerizing an olefin, comprising contacting the dimeric pyrrolecompound with a chromium-containing compound, a metal alkyl, ahalide-containing compound, a hydrocarbon solvent, or combinationsthereof.

Further disclosed herein is a method of making a catalyst for use inoligomerizing an olefin comprising a chromium-containing compound, apyrrole-containing compound, a metal alkyl, and a halide-containingcompound, comprising contacting the chromium-containing compound, thepyrrole-containing compound, the metal alkyl, or combinations thereofwith a previously prepared oligomerization catalyst composition.

Further disclosed herein is a method of making a catalyst for use inoligomerizing an olefin, comprising contacting a chromium-containingcompound, a pyrrole-containing compound, and a metal alkyl, with apreviously prepared oligomerization catalyst composition.

Further disclosed herein is a method of oligomerizing olefins comprising(a) preparing a catalyst by combining a chromium-containing compound, apyrrole-containing compound, a metal alkyl, a halide-containingcompound, and optionally a solvent; and (b) contacting the catalyst withthe olefin within about 1000 hours of preparation of the catalyst.

Further disclosed herein is an ethylene trimerization catalystcomprising a chromium-containing compound, a pyrrole-containingcompound, a metal alkyl, a halide-containing compound, and optionally asolvent, wherein 1-hexene produced by the catalyst has a purity of atleast about 98.8 at a time within about 800 hours after preparationcatalyst.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A through 1D illustrate various embodiments of a method ofpreparing an oligomerization catalyst comprising bulk addition ofcatalyst components.

FIGS. 2A through 2D illustrate various embodiments of a method forabating water in the preparing of an oligomerization catalyst.

FIGS. 3A through 3B illustrate various embodiments of a method forabating water in the preparing of an oligomerization catalyst.

FIGS. 4A through 4E illustrate various embodiments of a method ofpreparing an oligomerization catalyst comprising simultaneous additionof catalyst components.

FIG. 5 is a graph of the average catalyst residence time (i.e. catalystage) versus the purity of hexene produced.

DETAILED DESCRIPTION

As used herein, a catalyst component includes a chromium-containingcompound, a pyrrole-containing compound, a metal alkyl, ahalide-containing compound, a solvent, or combinations thereof. In thevarious embodiments disclosed herein, contacting of catalyst componentsmay occur in one or more contact zones. A contact zone is a zone inwhich the components are commingled and/or combined, and therebycontacted. The contact zone may be disposed in a vessel, e.g. a storagetank, tote, container, mixing vessel, reactor, etc.; a length of pipe,e.g. a tee, inlet, injection port, or header for combining componentfeed lines into a common line; or any other suitable apparatus forbringing the components into contact. As used herein, the termscontacted and combined refer to any addition sequence, order, orconcentration for contacting or combining two or more catalystcomponents. The term added to refers to a first catalyst componentadded, e.g., poured, into a second catalyst component. Where a firstcatalyst component is added to a second catalyst component, the initialconcentration, or molar ratio, of the first catalyst component comparedto the second catalyst component typically is relatively small andincreases over the duration of the addition. In some embodiments,contacting of components may occur in one or more upstream contactzone(s) prior to further contacting with other catalyst component(s) inone or more downstream contact zone(s). Where a plurality of contactzones are employed, contacting may occur simultaneously across thecontact zones, sequentially across the contact zones, or both, as issuitable for a given embodiment. Contacting may be carried out in abatch or continuous process, as is suitable for a given embodiment.

In embodiments utilizing a vessel for contacting the components, thecomponents may be optionally mixed by a mixer disposed in the vessel andthe formed mixture may then be removed for subsequent processing. Inembodiments utilizing a tee or other means for combing lines such as aheader, an optional in-line mixer may be placed in the commingledcatalyst feed line to ensure that adequate contacting of the combinedcomponents takes place, and the mixture is thus formed as it passesthrough the commingled feed line. Where a method of making a catalystrecites contact or combination of catalyst components, such may becarried out by contacting or combining all or a portion of suchcomponents in various embodiments.

As used herein, a composition comprising a catalyst component includesthe catalyst component alone or in combination with one or moreadditional compounds, solvents, or both. None, some, or all of thecontacting steps may be carried out in the presence of a solvent(sometimes referred to as an optional solvent), which may be introducedto a contact zone via inclusion with one or more compositions comprisinga catalyst component or may be introduced separately to a contact zone,for example in a solvent line or as an initial charge to a contact zone.

Disclosed herein is a method of making a catalyst comprising achromium-containing compound, a pyrrole-containing compound, a metalalkyl, a halide-containing compound, and optionally a solvent for use inoligomerizing an olefin, wherein a composition comprising thechromium-containing compound is contacted in a contact zone with acomposition comprising the metal alkyl. In FIG. 1, four embodiments forcontacting the composition comprising the chromium-containing compoundwith the composition comprising the metal alkyl in a contact zone areillustrated. FIGS. 1A through 1D are included as illustrativerepresentations of embodiments of the present disclosure and do notlimit the disclosure.

In an embodiment as illustrated in FIG. 1A, the composition comprisingthe metal alkyl may be disposed in contact zone 115 and the compositioncomprising the chromium-containing compound may be contacted with oradded to the composition comprising the metal alkyl present in contactzone 115 via line 110. The final catalyst composition may be recoveredas a product via line 170. The composition comprising thechromium-containing compound in line 110 may further comprise thepyrrole-containing compound, a non-metal halide-containing compound, thesolvent, or combinations thereof. The composition comprising thechromium-containing compound may also comprise an amount of non-halidemetal alkyl to abate undesired water, acidic protons, or both, asdisclosed in more detail herein. The final catalyst composition may befurther dilute with a solvent (which may not be identical to thecatalyst preparation solvent) prior to use in the oligomerizationreaction.

The composition comprising the metal alkyl present in contact zone 115,may comprise the pyrrole-containing compound, the halide-containingcompound, the solvent, or combinations thereof. The halide-containingcompound may be a metal halide, non-metal halide, or combinationsthereof. The composition comprising the metal alkyl may also comprise ametal alkyl halide, a non-halide metal alkyl, a non-metal halide, ametal halide, or combinations thereof. The metal alkyl halide in thisand other embodiments may comprise diethylaluminum chloride (DEAC) andthe non-halide metal alkyl may comprise triethyl aluminum (TEA). In anembodiment the metal alkyl may be the halide-containing compound, e.g.DEAC is the halide-containing compound and the metal alkyl.

In an embodiment as illustrated in FIG. 1B, a pyrrole-chromium mixturemay be formed in contact zone 225 by contacting a composition comprisingthe pyrrole-containing compound fed to contact zone 225 via line 220 andthe composition comprising the chromium-containing compound fed tocontact zone 225 via line 210, which may occur about instantaneously orover a first period of time of from about 1 minute to about 12 hours,alternatively from about 1 minute to about 6 hours, alternatively fromabout 1 minute to about 3 hours, alternatively from about 1 hour toabout 2 hours. Introduction of the composition comprising thechromium-containing compound and the composition comprising thepyrrole-containing compound to contact zone 225 may be sequential (e.g.chromium followed by pyrrole or vice-versa) or simultaneous. Once thepyrrole-chromium mixture has been contacted in contact zone 225 thepyrrole-chromium mixture from contact zone 225 may be contacted with oradded to the composition comprising the metal alkyl present in contactzone 215 via line 240, which may occur about instantaneously or over asecond period of time of from about 1 minute to about 12 hours,alternatively from about 1 minute to about 6 hours, alternatively fromabout 1 minute to about 3 hours, to form the final catalyst product incontact zone 215. The final catalyst product may be withdrawn fromcontact zone 215 via line 270. The final catalyst composition may befurther dilute with a solvent (which may not be identical to thecatalyst preparation solvent) prior to use in the oligomerizationreaction.

The composition comprising the pyrrole-containing compound in line 220and the composition comprising the chromium-containing compound in line210 may be contacted, e.g., over the first period of time, at an aboutconstant pyrrole to chromium (Py:Cr) molar ratio or alternatively at avariable Py:Cr molar ratio to form the pyrrole-chromium mixture incontact zone 225. The pyrrole-chromium mixture in contact zone 225 maythen be contacted with or added to, e.g., over the second period oftime, the metal alkyl present in contact zone 215 via line 240, oralternatively already present in contact zone 215, at an about constantPy:Cr molar ratio, for example in the range of from about 1.0:1 to about4.0:1. Alternatively, the pyrrole-chromium mixture in contact zone 225may then be contacted with or added to, e.g., over the second period oftime, the metal alkyl present in contact zone 215 via line 240 at avariable Py:Cr molar ratio. In an embodiment the variable Py:Cr molarratio is decreasing over the second period of time where a decreasingPy:Cr molar ratio refers to a general decreasing trend in the molarratio from the start of the addition sequence to the finish andoccasional increases in the ratio within the overall decreasing trendare acceptable. In an embodiment a decreasing trend of the Py:Cr refersto the specific situation where the ending Py:Cr ratio is less than thebeginning Py:Cr ratio. In an embodiment, an initial Py:Cr molar ratio atthe start of the addition may be greater than the final Py:Cr molarratio of the catalyst; and an ending Py:Cr molar ratio at the end of theaddition may be less than the final Py:Cr molar ratio of the catalyst.In an embodiment, the final Py:Cr molar ratio of the catalyst may be ina range of from about 1.0:1 to about 4.0:1; the initial Py:Cr molarratio may be greater than about 6:1, alternatively greater than about20:1, alternatively greater than about 40:1, alternatively greater thanabout 60:1; and the ending Py:Cr molar ratio may be greater than orequal to about 0, alternatively greater than or equal to about 0.1:1,alternatively greater than or equal to about 0.3:1, and alternativelygreater than or equal to about 0.6:1. In an embodiment, the initialPy:Cr molar ratio is about twice the final Py:Cr molar ratio of thecatalyst during a first about one-half of the addition and the endingPy:Cr molar ratio is about 0 during a second about one-half of theaddition, wherein the final Py:Cr molar ratio of the catalyst is in arange of from about 1.0:1 to about 4.0:1. Introduction of apyrrole-containing compound and a chromium-containing compound in acontact zone (e.g., formation of a Py:Cr mixture) as disclosed invarious embodiments may be carried out as disclosed in this paragraph,including but not limited to the embodiments shown in FIGS. 1D, 2C, 2D,3B, and 4A-E.

The composition comprising the chromium-containing compound in line 210may comprise a non-metal halide-containing compound, the solvent, orcombinations thereof. The composition comprising the pyrrole-containingcompound in line 220 may comprise a non-metal halide-containingcompound, the solvent, or combinations thereof. The compositioncomprising the chromium-containing compound in line 210, the compositioncomprising the pyrrole-containing compound in line 220, or both may alsocomprise an amount of non-halide metal alkyl to abate undesired water,acidic protons, or both as disclosed herein. Alternatively, thenon-halide metal alkyl may be contacted with or added to thepyrrole-chromium mixture, for example in line 240 via line 230, incontact zone 225 (not shown), or both, to abate undesired water, acidicprotons, or both. The composition comprising the metal alkyl present incontact zone 215, may comprise the halide-containing compound, thesolvent, or combinations thereof. The composition comprising the metalalkyl may also comprise a metal alkyl halide, a non-halide metal alkyl,a metal halide, non-metal halide, or combinations thereof.

In an embodiment as shown in FIG. 1C, a pyrrole-metal alkyl mixture maybe formed in contact zone 325 by contacting the composition comprisingthe pyrrole-containing compound fed to contact zone 325 via line 320with the composition comprising the metal alkyl fed to contact zone 325via line 315 which may occur about instantaneously or over a firstperiod of time. Addition of the composition comprising thepyrrole-containing compound and the composition comprising the metalalkyl to contact zone 325 may be sequential (e.g. pyrrole followed bymetal alkyl or vice-versa) or simultaneous. Once the pyrrole-metal alkylmixture has been contacted in contact zone 325 the pyrrole-metal alkylmixture from contact zone 325 may be disposed via line 360 in contactzone 335. The composition comprising the chromium-containing compoundmay then be contacted with or added to contact zone 335 via line 310,which may occur about instantaneously or over a second period of time.The composition comprising the chromium-containing compound is thuscontacted with or added to the pyrrole-metal alkyl mixture present incontact zone 335, to form the final catalyst product in contact zone335. Addition of the composition comprising the pyrrole-metal alkylmixture and the composition comprising the chromium-containing compoundto contact zone 335 may be sequential (e.g. pyrrole-metal alkyl followedby the chromium containing compound or vice-versa) or simultaneous. Thefinal catalyst product may be withdrawn from contact zone 335 via line370. The final catalyst composition may be further diluted with asolvent (which may not be identical to the catalyst preparation solvent)prior to use in the oligomerization reaction.

Although the embodiment shown in FIG. 1C shows two contact zones beingused to perform the addition sequences, the addition sequences couldalternatively be performed in a single contact zone, for example, incontact zone 325. In this embodiment, the composition comprising themetal alkyl may first be placed in the contact zone. In a second stepthe composition comprising the pyrrole-containing compound may becontacted with or added to the composition comprising the metal alkylpresent in the contact zone (or visa-versa) to adequately contact andform the pyrrole-metal alkyl mixture. In a third step, the compositioncontaining the chromium-containing compound may be contacted with oradded to the pyrrole-metal alkyl mixture to form the final catalystproduct.

The composition comprising the chromium-containing compound in line 310may comprise a non-metal halide-containing compound, the solvent, orcombinations thereof. The composition comprising the pyrrole-containingcompound in line 320 may comprise a non-metal halide-containingcompound, the solvent, or combinations thereof. The compositioncomprising the chromium-containing compound in line 310, the compositioncomprising the pyrrole-containing compound in line 320, or both maycomprise an amount of non-halide metal alkyl to abate undesired water,acidic protons, or both. The composition comprising the metal alkyl inline 315, may comprise the halide-containing compound, the solvent, orcombinations thereof. The composition comprising the metal alkyl mayalso comprise a metal alkyl halide, a non-halide metal alkyl, a metalhalide, non-metal halide, or combinations thereof.

In an embodiment as shown in FIG. 1D, a composition comprising thepyrrole-containing compound in line 420 and a composition comprising thechromium-containing compound in line 410 may be simultaneously contactedwith or added to, which may occur about instantaneously or over a periodof time, with a composition comprising the metal alkyl present incontact zone 415, and a final catalyst product may be withdrawn fromcontact zone 415 via line 470. The final catalyst composition may befurther diluted with a solvent (which may not be identical to thecatalyst preparation solvent) prior to use in the oligomerizationreaction. The composition comprising the chromium-containing compoundand the composition comprising the pyrrole-containing compound may becontacted with or added to the composition comprising the metal alkyl atPy:Cr molar ratios described previously.

The composition comprising the chromium-containing compound in line 410may comprise a non-metal halide-containing compound, the solvent, orcombinations thereof. The composition comprising the pyrrole-containingcompound in line 420 may comprise a non-metal halide-containingcompound, the solvent, or combinations thereof. In the embodiment shownin FIG. 1D, the composition comprising the metal alkyl in contact zone415, may comprise the halide-containing compound, the solvent, orcombinations thereof, each added to contact zone 415 through variousinput lines not shown in FIG. 1D. The composition comprising the metalalkyl may also comprise a metal alkyl halide, a non-halide metal alkyl,a metal halide, non-metal halide, or combinations thereof. Thecomposition comprising the chromium-containing compound in line 410, thecomposition comprising the pyrrole-containing compound in line 420, orboth may comprise an amount of non-halide metal alkyl to abate undesiredwater, acidic protons, or both.

Further disclosed herein is a method of making a catalyst comprisingabating all or a portion of water, acidic protons, or both from acomposition comprising the chromium-containing compound, a compositioncomprising the pyrrole-containing compound, a composition comprising thenon-metal halide-containing compound, a composition comprising thesolvent, or combinations thereof prior to contact thereof with acomposition comprising the metal halide-containing compound. Abatingwater, acidic protons, or both may include neutralizing acidic protons;physically removing water; physically removing acidic protons;chemically binding or reacting free water such that the water is nolonger free; or combinations thereof. The amount of water, acid protons,or both removed from the catalyst component may be determined usingknown methods, for example infrared analysis to determine water content.

In embodiments to prepare a catalyst, one or more of the catalystcomponents may contain water, for example the composition comprising thechromium-containing compound. Water may be present in a catalystcompound, for example as a contaminant or as a co-product producedduring the preparation of the catalyst compound. For example, water maybe co-produced during preparation of the chromium-containing compound,and such water may complex with the chromium. Acidic protons may also bepresent, for example carboxylic acid (e.g., ethylhexanoic acid)remaining from production of the chromium-containing compound (e.g.,chromium tris(2-ethylhexanoate)). This free water as well as acidpresent in the chromium source can subsequently react with a metalhalide present in the catalyst, for example the metal alkyl halide suchas DEAC, to form corrosive compounds, e.g. hydrogen halide compound(e.g. hydrochloric acid). Such compounds may cause corrosion indownstream equipment over time, in particular when heated, for examplein downstream fractionation facilities. Accordingly, it may be desirableto abate water, acidic protons, or both, when making the catalyst toprevent downstream formation of potentially corrosive by-products.

Furthermore, in embodiments of a method of preparing a catalyst,impurities in the catalyst components can participate in unwanted sidereactions leading to the formation of precipitates. These precipitatesmay to lead to further unwanted reactions, for example polymer formationin the trimerization of ethylene to 1-hexene. Water may be an initiatorof the precipitation reactions and therefore may be desirably abatedfrom the catalyst components to improve selectivity to 1-hexene. Abatingwater, acidic protons, or both may also have beneficial impact oncatalyst efficiency, even where corrosive compounds are produced. Forexample, in an embodiment, water is abated from one or more catalystcomponents by contact thereof with a corrosive abatement compound suchas a halide-containing compound, which reacts with and abates the water.Reactions of water with a corrosive abatement compound such as ahalide-containing compound may produce a corrosive compound, e.g., HCl,and such should be taken into account in the overall design of thesystem. Examples of suitable halide-containing compounds for reactionwith water include a metal halide, a metal alkyl halide, a non-halidemetal alkyl and a metal halide, a non-metal halide, or combinationsthereof. The use of a halide-containing compound to abate water may beused in place of or in addition to other water abatement embodimentsdisclosed herein such as the use of a non-halide metal alkyl to abatewater.

In an embodiment, water, acidic protons, or both may be abated bypre-contacting one or more catalyst components with a non-corrosiveabatement compound, which is a compound that does not form a corrosivecompound such as a hydrogen halide compound upon contact with the water,acidic protons, or both. Non-corrosive abatement compounds include, forexample, a non-halide metal alkyl such as TEA. Corrosive abatementcompounds are compounds that can form a corrosive compound upon contactwith water, acidic protons or both such as (i) a metal alkyl halide,(ii) a metal halide and a metal alkyl, and (iii) a non-metal halide anda metal alkyl. The corrosive abatement compounds also include any othercombination of compounds that form a corrosive compound upon contactwith water, acidic proton, or both.

In an embodiment, one or more catalyst components such as a compositioncomprising the chromium-containing compound, a composition comprisingthe pyrrole-containing compound, a non-metal halide-containing compound,a solvent, or combinations thereof, are contacted with a non-halidemetal alkyl to abate water, acidic protons, or both. The non-halidemetal alkyl can react with free water, acid protons, or both containedin the catalyst component(s) when pre-contacted to abate water, acidicprotons, or both. The non-halide metal alkyl may be pre-mixed in acontact zone with the one or more catalyst components. The pre-mix maybe made by either adding the non-halide metal alkyl to the catalystcomponent(s) or vice versa, and in an embodiment, the pre-mix may bemade by adding the non-halide metal alkyl to the catalyst component(s).These additions can be made in various ratios as described below.

In an embodiment, the non-halide metal alkyl in added to or contactedwith a composition comprising the chromium-containing compound. Giventhat the chromium may react with the non-halide metal alkyl to form agel, it may be desirable to maintain a low concentration of non-halidemetal alkyl by adding it to the composition comprising thechromium-containing compound, so that there may only be an amountavailable to react with the water and acid. Conversely, with a highconcentration of non-halide metal alkyl, such as can occur when addingthe composition comprising the chromium-containing compound to thenon-halide metal alkyl, more non-halide metal alkyl would be availableto react with the chromium (and thereby form a gel) after the water andacid were removed.

In each embodiment, the water or acid abating substance (e.g., anon-halide metal alkyl) may be contacted with or added to one or morecatalyst components in an amount effective to abate substantially allfree/available water, acidic protons, or both from some or all of thecomponents contacted with the non-halide metal alkyl. In an embodiment,the amount of non-halide metal alkyl contacted with or added to suchcomponents is small relative to the amount of the catalyst components towhich it is being contacted with or added to. In an embodiment, theportion of the non-halide metal alkyl contacted with or added to acatalyst component(s) may be less than or equal to about 30 weightpercent of the catalyst component(s) to which it is contacted with oradded to; alternatively less than about 20 weight percent of thecatalyst component(s) to which it is contacted with or added to;alternatively less than about 10 weight percent of the catalystcomponent(s) to which it is contacted with or added to; alternativelyless than about 5 weight percent of the catalyst component(s) to whichit is contacted with or added to. In an embodiment, the portion of thenon-halide metal alkyl contacted with or added to a catalystcomponent(s) may be less than or equal to about 120 mole percent of thecatalyst component(s) to which it is contacted with or added to;alternatively less than about 80 mole percent of the catalystcomponent(s) to which it is contacted with or added to; alternativelyless than about 40 mole percent of the catalyst component(s) to which itis contacted with or added to; alternatively less than about 20 molepercent of the catalyst component(s) to which it is contacted with oradded to. The non-halide metal alkyl may be contacted with or added to acatalyst component(s) in an amount such that the non-halide metal alkylto catalyst component(s) molar ratio may be less than about 1.5:1,alternatively less than about 1.2:1, alternatively less than about 1:1.The non-halide metal alkyl may be contacted with or added to a catalystcomponent(s) in a molar ratio sufficient to abate at least about 25% ofthe water, acidic protons, or both associated with the catalystcomponent(s) present in the pre-contacting contact zone; alternativelyat least about 90% of the water, acidic protons, or both associated withthe catalyst component(s) present in the pre-contacting contact zone;alternatively at least about 100% of the water, acidic protons, or bothassociated with the catalyst component(s) present in the pre-contactingcontact zone; alternatively in an amount that may be at least about 10%in excess of an amount sufficient to abate at least about 100% of thewater, acidic protons, or both associated with the catalyst component(s)present in the pre-contacting contact zone; alternatively in an amountthat may be at least about 20% in excess of an amount sufficient toabate at least about 100% of the water, acidic protons, or bothassociated with the catalyst component(s) present in the pre-contactingcontact zone; alternatively in an amount that may be at least about 30%in excess of an amount sufficient to abate at least about 100% of thewater, acidic protons, or both associated with the catalyst component(s)present in the pre-contacting contact zone; alternatively in an amountthat may be at least about 100% in excess of an amount sufficient toabate at least about 100% of the water, acidic protons, or bothassociated with the catalyst component(s) present in the pre-contactingcontact zone; or alternatively in an amount that may be at least about200% in excess of an amount sufficient to abate at least about 100% ofthe water, acidic protons, or both associated with the catalystcomponent(s) present in the pre-contacting contact zone.

Upon abatement of water, acidic protons, or both from one or morecatalyst components, such abated catalyst components may be stored untilneeded for preparation of a catalyst composition. Such storage may ormay not be in the presence of a solvent. The pre-mix comprising aportion of non-halide metal alkyl and one or more abated catalystcomponent(s) may then be contacted with the remaining catalystcomponents including the metal alkyl halide to form the final catalystproduct. The remaining catalyst components may also comprise additionalnon-halide metal alkyl to comprise the total non-halide metal alkylcomposition in the final catalyst. In an embodiment, the additionalnon-halide metal alkyl may be the same as that used in the pre-mix.Alternatively, the additional non-halide metal alkyl may be differentfrom that used in the pre-mix.

FIGS. 2A-2D represent various embodiments for abating water, acidicprotons, or both in the composition comprising the chromium-containingcompound, the composition comprising the pyrrole-containing compound, orboth prior to contact with the composition comprising a metalhalide-containing compound. FIGS. 2A through 2D are included asillustrative representations of embodiments of the present disclosureand do not limit the disclosure. Furthermore, various embodiments forabating water, acidic protons, or both may be combined to increaseoverall effectiveness.

The composition comprising a chromium-containing compound may becontacted with the non-halide metal alkyl to form a mixture prior tocontacting the mixture with the remaining catalyst components. In anembodiment shown in FIG. 2A a composition containing thechromium-containing compound may be disposed in contact zone 510, theplacement of which may take place via input line 505. The composition incontact zone 510 may optionally contain solvent, other catalystcomponents, or combinations thereof, provided that contact zone 510 doesnot comprise (i) a metal alkyl halide, (ii) a metal halide and a metalalkyl, or (iii) a non-metal halide and a metal alkyl. Non-halide metalalkyl, optionally in solvent, may be added to the composition containinga chromium-containing compound in contact zone 510 via line 530. Thenon-halide metal alkyl may be added in an amount less than or equal toabout 30 weight percent of the composition containing thechromium-containing compound to which it is added or in other amounts asdisclosed herein.

The resultant mixture in contact zone 510 may then be passed fromcontact zone 510 via line 511 and optionally fed into a filter 512,comprising dry (free of any water) filter medium, for filtering anyprecipitate that may have formed from the mixture. The precipitate maybe filtered and the filtrate may be passed via line 513 into contactzone 515 for contacting with the remaining catalyst components includinga composition comprising the metal alkyl, the pyrrole-containingcompound, the halide-containing compound (e.g., a metal halide ornon-metal halide), the solvent, any remaining non-halide metal alkyl,metal alkyl halide, or combinations thereof, which may be placed intocontact zone 515 via various input lines not shown in FIG. 2A. Acatalyst product may then be withdrawn from contact zone 515 via line570. Where filtering is omitted, the remaining catalyst components maybe alternatively contacted in contact zone 510.

The composition comprising a pyrrole-containing compound may becontacted with the non-halide metal alkyl to form a mixture prior tocontacting the mixture with the remaining catalyst components. In anembodiment shown in FIG. 2B a composition comprising apyrrole-containing compound may be disposed in contact zone 620 viainput line 607. The composition in contact zone 620 may optionallycontain solvent, other catalyst components, or combinations thereof,provided that contact zone 620 does not comprise (i) a metal alkylhalide, (ii) a metal halide and a metal alkyl, or (iii) a non-metalhalide and a metal alkyl. Non-halide metal alkyl, which may be insolvent, may be added to the composition containing a pyrrole-containingcompound in contact zone 620 via line 630. The non-halide metal alkylmay be added in an amount less than or equal to about 10 weight percentof the composition containing the pyrrole-containing compound to whichit is added or in other amounts as disclosed herein.

The resultant mixture in contact zone 620 may then be passed fromcontact zone 620 via line 621 and optionally filtered (not shown) toremove any precipitate that may have formed in the mixture. Theresultant mixture may then be fed into contact zone 615 for contactingwith the remaining catalyst components including a compositioncomprising the metal alkyl, the chromium-containing compound, thehalide-containing compound (e.g., a metal halide or non-metal halide),the solvent, any remaining non-halide metal alkyl, metal alkyl halide,or combinations thereof, which may be placed into contact zone 615 viavarious input lines not shown in FIG. 2B. A catalyst product may then bewithdrawn from contact zone 615 via line 670. Where filtering isomitted, the remaining catalyst components may be alternativelycontacted in contact zone 620 via various input lines not shown in FIG.2B.

The composition comprising the chromium containing compound may becontacted with the composition comprising the pyrrole-containingcompound to form a mixture prior to contacting the mixture with thenon-halide metal alkyl. In an embodiment as illustrated in FIG. 2C, apyrrole-chromium mixture may be formed in contact zone 725 by contactinga composition comprising the pyrrole-containing compound fed to contactzone 725 via line 720 and the composition comprising thechromium-containing compound fed to contact zone 725 via line 710, whichmay occur about instantaneously or over a first period of time. Feedingof the composition comprising the chromium-containing compound and thecomposition comprising the pyrrole-containing compound to contact zone725 may be sequential (e.g. chromium followed by pyrrole or vice-versa)or simultaneous and at constant or varying Py:Cr ratios as disclosedpreviously. Once the pyrrole-chromium mixture has been contacted incontact zone 725 the pyrrole-chromium mixture from contact zone 725 maybe placed in contact zone 731 via line 740. The pyrrole-chromium mixturemay optionally contain solvent, other catalyst components, orcombinations thereof, but does not comprise (i) a metal alkyl halide,(ii) a metal halide and a metal alkyl, or (iii) a non-metal halide and ametal alkyl. Non-halide metal alkyl, which may be in solvent, may beadded to the pyrrole-chromium mixture in contact zone 731 via line 730.The non-halide metal alkyl may be added in an amount less than or equalto about 10 weight percent of the pyrrole-chromium mixture to which itis added or in other amounts as disclosed herein. Although not shown inFIG. 2C, contact zone 725 and contact zone 731 may be the same contactzone providing that the addition sequence as described above remains thesame.

The resultant mixture in contact zone 731 may then be passed fromcontact zone 731 via line 732 and may optionally be filtered (not shown)to remove any precipitate that may have formed in the mixture. Themixture may be fed into contact zone 715 for contacting with theremaining catalyst components including a composition comprising themetal alkyl, the halide-containing compound (e.g., a metal halide ornon-metal halide), the solvent, any remaining non-halide metal alkyl,metal alkyl halide, or combinations thereof, which may be placed intocontact zone 715 via various input lines not shown in FIG. 2C. Acatalyst product may then be withdrawn from contact zone 715 via line770 and may optionally be filtered in a filter (not shown). Wherefiltering is omitted, remaining catalyst components may be alternativelycontacted in contact zone 725 or 731.

The composition comprising a chromium-containing compound may becontacted with the non-halide metal alkyl to form a first mixture; thecomposition comprising a pyrrole-containing compound may be contactedwith the non-halide metal alkyl to form a second mixture; and the firstand second mixtures may be contacted with the remaining catalystcomponents. In an embodiment shown in FIG. 2D a composition containing achromium-containing compound may be disposed in contact zone 810, theplacement of which takes place via input line 805. The composition incontact zone 810 may optionally contain solvent, other catalystcomponents, or combinations thereof, but contact zone 810 does notcomprise (i) a metal alkyl halide, (ii) a metal halide and a metalalkyl, or (iii) a non-metal halide and a metal alkyl. Non-halide metalalkyl, which may be in solvent, may be added to the compositioncontaining a chromium-containing compound in contact zone 810 via line830 forming a first mixture. The non-halide metal alkyl may be added inan amount less than or equal to about 10 weight percent of thecomposition containing the chromium-containing compound to which it isadded or in other amounts as disclosed herein.

A second mixture can be formed in contact zone 820. The compositioncomprising a pyrrole-containing compound may be disposed in contact zone820, the placement of which takes place via input line 807. Thecomposition comprising a pyrrole-containing compound in contact zone 820may optionally contain solvent, other catalyst components, orcombinations thereof, but does not comprise (i) a metal alkyl halide,(ii) a metal halide and a metal alkyl, or (iii) a non-metal halide and ametal alkyl. Non-halide metal alkyl, which may be in solvent, may beadded to the composition containing a pyrrole-containing compound incontact zone 820 via line 831 forming the second mixture. The non-halidemetal alkyl may be added in an amount less than or equal to about 10weight percent of the composition containing the pyrrole-containingcompound to which it is added or in other amounts as disclosed herein.

The first mixture, second mixture, or both may optionally be filtered(not shown) to remove any precipitate that may have formed in themixtures. Optionally, either the first, second, or both mixtures may bestored. The first and second mixtures may then be fed into contact zone815 via lines 811 and 821, respectively for contacting with theremaining catalyst components including the composition comprising metalhalide. Alternatively, although not shown in FIG. 2D the first andsecond mixtures may be contacted separately in another contact zoneprior to being fed via a commingled feed line into contact zone 815, andsuch commingled feed line may be optionally filtered to remove anyprecipitate that may have formed. Contact zone 815 initially may becomprised of a composition comprising the metal alkyl, ahalide-containing compound (e.g., a metal halide or non-metal halide), asolvent, the remaining non-halide metal alkyl, metal alkyl halide, orcombinations thereof, all of which have been placed into contact zone815 via various input lines not shown in FIG. 2D. A catalyst product maythen be withdrawn from contact zone 815 via line 870 and optionallyfiltered (filter not shown). In alternative embodiments, remainingcatalyst components may be contacted in contact zone 810 or 820.

The addition of the composition comprising the pyrrole-containingcompound and the composition comprising the chromium-containing compoundas shown in FIGS. 2C and 2D may be made in constant or varying Py:Crratios as disclosed previously.

Water may be removed from the chromium-containing compound prior tocontact with the metal halide-containing compound according to variouswater abatement embodiment disclosed herein. In an embodiment, thechromium-containing catalyst feedstock may be contacted with anazeotropic solvent such as an aromatic compound, paraffin solvent,chlorinated solvent, other solvent, or mixture of solvents capable offorming an azeotrope with water. The azeotropic solvent, thechromium-containing compound, and any water present form a solution andthe solution may be subjected to an azeotropic distillation to removethe water, wherein the solvent-water azeotrope is a lower boilingcomponent. Optionally, the solvent used to remove water by azeotropicdistillation may be recovered after the azeotropic distillation. In anembodiment, the azeotropic solvent used to remove water using azeotropicdistillation may comprise ethylbenzene, benzene, meta-xylene,ortho-xylene, para-xylene, mixed xylenes, toluene, octane, nonane,heptane, hexane, mixed hexanes, cyclohexane, carbon tetrachloride,chloroform, dichloromethane, 1,1,2 trichloroethane, or combinationsthereof. The amount of water removed from a catalyst component byvarious abatement methods may be monitored using known analyticalmethods such as infrared analysis.

In an embodiment shown in FIG. 3A a composition containing achromium-containing compound may be disposed in contact zone 910, theplacement of which takes place via an input line 905. The composition incontact zone 910 may optionally contain solvent, other catalystcomponents, or combinations thereof, but contact zone 910 does notcomprise (i) a metal alkyl halide, (ii) a metal halide and a metalalkyl, or (iii) a non-metal halide and a metal alkyl. An azeotropicsolvent, e.g., a composition comprising an aromatic compound such asethylbenzene, may be added to the composition containing achromium-containing compound in contact zone 910 via line 902 ordirectly added to separator 900. The azeotropic solvent may be added inan amount effective to form an azeotropic solution with thechromium-containing compound. In an embodiment, the azeotropic solventmay be added in an amount from about 0.5 to about 1000 times the weightof the composition containing the chromium-containing compound to whichit is added, alternatively from about 0.5 to about 500 times the weight,alternatively from about 0.5 to about 100 times the weight,alternatively from about 0.5 to about 50 times the weight, alternativelyfrom about 0.5 to about 25 times the weight, alternatively from about0.5 to about 15 times the weight. The resultant azeotropic solution incontact zone 910 may then be passed from contact zone 910 via line 911and fed into a separator 900 for the azeotropic distillation of thesolution to remove the water. Operating temperature of separator 900will depend on the azeotropic solvent used and the pressure maintainedon the separator. The water may be removed from separator 900 throughoverhead line 912, optionally the aromatic compound recovered, and theremaining abated components may be fed via line 913 into contact zone915 for contacting with the remaining catalyst components including thecomposition comprising the metal alkyl, the pyrrole-containing compound,the halide-containing compound (e.g., a metal halide or non-metalhalide), the catalyst solvent, any remaining non-halide metal alkyl,metal alkyl halide, or combinations thereof, which may be placed intocontact zone 915 via various input lines not shown in FIG. 3A. Acatalyst product may then be withdrawn from contact zone 915 via line970 and optionally filtered (not shown). Alternatively the water abatedmaterial comprising the chromium-containing compound may be stored priorto contact with the remaining catalyst components. Optionally, theabated components from line 913 may be subjected to further waterabatement as described herein, for example contact with a non-halidemetal alkyl, adsorbent, or both prior to contact with the remainingcatalyst components.

In an embodiment, one or more catalyst components other than (i) a metalalkyl halide, (ii) a metal halide and a metal alkyl, or (iii) anon-metal halide and a metal alkyl, for example the compositioncomprising the chromium-containing compound, the composition comprisingthe pyrrole-containing compound, the non-metal halide-containingcompound, the solvent, or combinations thereof are contacted with anadsorbent to abate water. The contacting may occur prior to contactingwith (i) a metal alkyl halide, (ii) a metal halide and a metal alkyl, or(iii) a non-metal halide and a metal alkyl. In some embodiments,contacting the chromium-containing compound with the pyrrole-containingcompound may enhance the solubility of the chromium-containing compoundin a solvent (e.g. ethylbenzene) as well as reduce the solutionviscosity. Thus, the reduced viscosity and more soluble solution mayenhance the suitability of the solution to water abatement by means ofpassing it through an adsorbent such as molecular sieves, to remove allor a portion of any water present. In an embodiment, the pyrrole addedmay constitute substantially all or only a portion of the pyrrolerequired to make the catalyst composition. Other known means forreducing viscosity, enhancing solubility, or both may be employed suchthat a catalyst component becomes suitable for contact with an adsorbentto remove water.

Adsorption as used herein refers to the separation operation in whichone component of a gas or liquid mixture is selectively retained in thepores of a resinous or microcrystalline solid. A gas or liquid mixturecontacts a solid (the adsorbent) and a mixture component (the adsorbate,which is typically water) adheres to the surface of the solid. In anembodiment, an adsorbent may be used to abate water by adding theadsorbent to catalyst component(s) in a vessel and mixing thoroughly foradequate contacting of the adsorbent with the catalyst component(s). Themixture may then be allowed to stand and after a period of time, theadsorbent settles to the bottom of the vessel. Separation can becompleted by decanting or filtration (e.g., suction filtration).Alternatively, water may be abated by passing the catalyst component(s)through a fixed adsorption bed comprised of an adsorbent, allowing themixture adequate contact time for the adsorbate to sufficiently adhereto the adsorbent, and then removing the abated catalyst component(s)from the adsorption bed. The adsorbent may then be replaced orregenerated for the next use. The original adsorption capacity of thesaturated bed may be recovered by any suitable regeneration method, forexample, thermal regeneration, regeneration by pressure swing, orregeneration by purging.

In the embodiments, any suitable adsorbent may be used. Examples ofsuitable adsorbents include 3-Angstrom molecular sieves, 5-Angstrommolecular sieves, 13X molecular sieves, alumina, silica, or combinationsthereof. 3-Angstrom (3 A) and 5-Angstrom (5 A) refers to the size of themolecule the material can adsorb, for example, the 3 A molecular sievecan adsorb molecules less than 3 angstrom and the 5 A molecular sievecan adsorb molecules less than 5 angstrom. Molecular sieves arecrystalline structures not unlike sponges on a molecular scale. Theyhave a solid framework defining large internal cavities where moleculescan be adsorbed. These cavities are interconnected by pore openingsthrough which molecules can pass. Because of their crystalline nature,the pores and cavities are the same size, and depending on the size ofthe openings, they can adsorb molecules readily, slowly, or not at all,thus functioning as molecular sieves—adsorbing molecules of certainsizes while rejecting larger ones.

In an embodiment as illustrated in FIG. 3B, a pyrrole-chromium mixturemay be formed in contact zone 1025 by contacting a compositioncomprising the pyrrole-containing compound fed to contact zone 1025 vialine 1020 and the composition comprising the chromium-containingcompound fed to contact zone 1025 via line 1010, which may occur aboutinstantaneously or over a first period of time. Feeding of thechromium-containing composition and the pyrrole-containing compositionto contact zone 1025 may be sequential (e.g. chromium followed bypyrrole or vice-versa) or simultaneous and at constant or varying Py:Crratios as disclosed previously. Once the pyrrole-chromium mixture hasbeen contacted in contact zone 1025 the pyrrole-chromium mixture fromcontact zone 1025 may be passed to contact zone 1000 via line 1040. Thepyrrole-chromium mixture may optionally contain solvent, other catalystcomponents, e.g. a non-metal halide, or combinations thereof, but doesnot comprise (i) a metal alkyl halide, (ii) a metal halide and a metalalkyl, or (iii) a non-metal halide and a metal alkyl. Thepyrrole-chromium mixture is contacted with an adsorbent disposed incontact zone 1000. Contact zone 1000 may be a fixed adsorption bed asdescribed in a previous embodiment, sized accordingly to the volumes ofmaterials being adsorbed. The pyrrole-chromium mixture may be passedthrough the adsorption bed comprised of an adsorbent, e.g. 3 A molecularsieve, allowing for the adsorption process to occur over a second periodof time to adsorb essentially all of the free water from thepyrrole-chromium mixture. Contact with the adsorbent in contact zone1000 may be carried out according to various known methods.

The water abated mixture in contact zone 1000 may then be passed fromcontact zone 1000 via line 1018 and contacted with the remainingcatalyst components in contact zone 1015 including the compositioncomprising the metal alkyl, a halide-containing compound (e.g., a metalhalide or non-metal halide), the solvent, any remaining non-halide metalalkyl, metal alkyl halide, or combinations thereof, which may be placedinto contact zone 1015 via various input lines not shown in FIG. 3B. Acatalyst product may then be withdrawn from contact zone 1015 via line1070 and optionally filtered (not shown). Alternatively the water abatedmaterial comprising the chromium-containing compound may be stored priorto contact with the remaining catalyst components. Optionally, the waterabated compounds from contact zone 1000 may be subjected to furtherwater abatement as described herein, for example contact with anon-halide metal alkyl, azeotropic distillation, or both prior tocontact with the remaining catalyst components.

Embodiments for abating water, acidic protons, or both as disclosedherein, for example the embodiments shown in FIGS. 2A-2D and 3A-3B, maybe applied alone or in combination to other processes and catalystcompositions known in the art, for example, water, acidic protons, orboth may be abated from the catalyst compositions or componentsdisclosed in reference U.S. Pat. No. 6,133,495, U.S. App. No.2002/0035029, WO 01/83447, WO 03/053890, and WO 03/053891, each of whichis incorporated herein in its entirety. Likewise, embodiments forpreparing catalysts, for example embodiments shown in FIGS. 1A-1D and4A-4E, may be applied alone or in combination to other processes andcatalyst compositions known in the art, for example those set forth inU.S. Pat. No. 6,133,495, 2002/0035029, WO 01/83447, WO 03/053890, and WO03/053891. When applying the water abatement and catalyst preparationembodiments to these catalyst compositions or components disclosed inreference U.S. Pat. No. 6,133,495, U.S. App. No. 2002/0035029, WO01/83447, WO 03/053890, and WO 03/053891, the appropriate substitutionsand adjustment should be made for components that have a similarfunction; e.g. substitution of the multidentate ligands of WO 03/053890and WO 03/053891 for the pyrrole compound used herein and adjustments ofthe ligand:Cr (pyrrole:chromium) molar ratios to account for the numberof equivalents of ligand(s) per mole of the ligand. Furthermore,catalyst compositions or components disclosed in reference U.S. Pat. No.6,133,495, U.S. App. No. 2002/0035029, WO 01/83447, WO 03/053890, and WO03/053891 may be combined with other catalyst compositions or componentsas set forth herein to make various final catalysts according to variousembodiments described herein, and water may be abated from any one ormore of such compositions or components by any one or more abatementmethod disclosed herein.

In an embodiment, water, acidic protons, or both may be abated from thecatalyst composition for producing an alpha-olefin oligomer disclosed inU.S. Pat. No. 6,133,495. A chromium-based catalyst is prepared bybringing a pyrrole ring-containing compound, an alkyl aluminum compound,and a halogen-containing compound into contact with each other in ahydrocarbon solvent, halogenated hydrocarbon solvent or mixture thereof,and then bringing the mixed resultant solution into contact with thechromium compound, wherein water, acidic protons, or both are abatedfrom the catalyst or a component thereof prior to or during preparationof the catalyst. In an embodiment, the chromium-based catalyst isprepared by bringing the chromium compound, the pyrrole ring-containingcompound, the alkyl aluminum compound, and the halogen-containingcompound into contact with each other in a hydrocarbon solvent,halogenated hydrocarbon solvent or mixture thereof in the absence ofalpha-olefin under such a condition that the concentration of thechromium compound in the resultant mixed solution is about 1×10⁻⁷ to 1mol/liter, alternatively about 1×10⁻⁵ to 3×10⁻² mol/liter, alternativelyadjusted to not more than about 8×10⁻³ mol/liter, alternatively, notmore than about 0.416 mg Cr/mL, wherein water, acidic protons, or bothare abated from the catalyst or a component thereof prior to or duringpreparation of the catalyst. In an embodiment, water, acidic protons, orboth are abated from a catalyst component comprising a pyrrolederivative represented by the general formula (I):

wherein R¹ to R⁴ are a hydrogen atom or a linear or branched hydrocarbongroup having 1 to 20 carbon atoms, in which R³ and R⁴ may integrallyform a ring; X is a halogen atom; M is an element selected from thegroup consisting of those belonging to 3-Group, 4-Group, 6-Group(exclusive of chromium), 13-Group, 14-Group and 15-Group of the PeriodicTable; m and n are numbers satisfying the relationships of 1≦m≦6, 0≦n≦5and 2≦m+n≦6 with the provis that the sum of m and n is identical to thevalence of the element M; n represents the number of Rs; and R is ahydrogen atom or a linear or branched hydrocarbon group having 1 to 20carbon atoms and when n is not less than 2, and Rs may be the same ordifferent.

In an embodiment, water, acidic protons, or both may be abated from thecatalyst composition disclosed in US Patent No. 2002/0035029. In anembodiment, a catalyst for trimerization of ethylene comprises:

(i) an organometallic complex having a neutral multidentate ligandhaving a tripod structure, represented by the following formula (1):

AMQ_(n)   (1)

wherein A may be a neutral multidentate ligand having a tripodstructure, M may be a transition metal atom of group 3 to group 10 ofthe periodic table, each Q may be independently selected from the groupconsisting of a hydrogen atom, a halogen atom, a straight chain orbranched alkyl group having 1 to 10 carbon atoms which may have asubstituent, an aryl group having 6 to 10 carbon atoms which may have asubstituent, and n is an integer equal to a formal oxidation valence ofM, and

(ii) an alkylaluminoxane;

said neutral multidentate ligand A in formula (1) being a tridentateligand represented by the following formula (2) or formula (3):

wherein j, k and m independently represent an integer of 0 to 6, each D¹independently represents a divalent hydrocarbon group which may have asubstituent, each L¹ independently represents a substituent containingan element of group 14, 15, 16 or 17 of the periodic table, with theproviso that all of the three L¹s are not concurrently a substituentcontaining an element of group 14 or 17, G¹ represents a carbon orsilicon atom, and R¹ represents a hydrogen atom, an alkyl group having 1to 10 carbon atoms which may have a substituent, or an aryl group having6 to 10 carbon atoms which may have a substituent;

wherein a, b and c independently represent an integer of 0 to 6; urepresents an integer of 0 or 1; each D² independently represents adivalent hydrocarbon group which may have a substituent; each L²independently represents a substituent containing an element of group14, 15, 16 or 17 of the periodic table, with the proviso that all of thethree L²s are not concurrently a substituent containing an element ofgroup 14 or 17, G² represents a nitrogen or phosphorus atom when u is 0,or a phosphorus atom when u is 1, and R² represents an oxygen or sulfuratom. Water, acidic protons, or both may be abated from the catalyst ora component thereof prior to or during preparation of the catalyst.

In an embodiment, a catalyst for trimerization of ethylene comprises:

-   -   (i) an organometallic complex having a neutral multidentate        ligand having a tripod structure, represented by the following        formula (1):

AMQ_(n)   (1)

wherein A is a neutral multidentate ligand having a tripod structure, Mis a transition metal atom of group 3 to group 10 of the periodic table,each Q is independently selected from the group consisting of a hydrogenatom, a halogen atom, a straight chain or branched alkyl group having 1to 10 carbon atoms which may have a substituent, an aryl group having 6to 10 carbon atoms which may have a substituent, and n is an integerequal to a formal oxidation valence of M, and

(ii) an alkylaluminoxane, and

(iii) a halogenated inorganic compound;

said neutral multidentate ligand A in formula (1) being a tridentateligand represented by the following formula (2) or formula (3):

wherein j, k and m independently represent an integer of 0 to 6, each D¹independently represents a divalent hydrocarbon group which may have asubstituent, each L¹ independently represents a substituent containingan element of group 14, 15, 16 or 17 of the periodic table, with theproviso that all of the three L¹s are not concurrently a substituentcontaining an element of group 14 or 17, G¹ represents a carbon orsilicon atom, and R¹ represents a hydrogen atom, an alkyl group having 1to 10 carbon atoms which may have a substituent, or an aryl group having6 to 10 carbon atoms which may have a substituent;

wherein a, b and c independently represent an integer of 0 to 6; urepresents an integer of 0 or 1; each D² independently represents adivalent hydrocarbon group which may have a substituent; each L²independently represents a substituent containing an element of group14, 15, 16 or 17 of the periodic table, with the proviso that all of thethree L²s are not concurrently a substituent containing an element ofgroup 14 or 17, G² represents a nitrogen or phosphorus atom when u is 0,or a phosphorus atom when u is 1, and R² represents an oxygen or sulfuratom. Water, acidic protons, or both may be abated from the catalyst ora component thereof prior to or during preparation of the catalyst.

In an embodiment, a catalyst for trimerization of ethylene comprises:

(i) an organometallic complex having a neutral multidentate ligandhaving a tripod structure, represented by the following formula (1):

AMQ_(n)   (1)

wherein A is a neutral multidentate ligand having a tripod structure, Mis a transition metal atom of group 3 to group 10 of the periodic table,each Q is independently selected from the group consisting of a hydrogenatom, a halogen atom, a straight chain or branched alkyl group having 1to 10 carbon atoms which may have a substituent, an aryl group having 6to 10 carbon atoms which may have a substituent, and n is an integerequal to a formal oxidation valence of M,

(ii) an alkylaluminoxane,

(iii) a halogenated inorganic compound, and

(iv) an alkyl group-containing compound represented by the followingformula (4):

R_(p)EJ_(q)   (4)

wherein p and q are numbers satisfying the formulae: 0<p≦3 and 0≦q<3,provided that (P+q) is in the range of 1 to 3, E represents an atom,other than a hydrogen atom, of group 1, 2, 3, 11, 12 or 13 of theperiodic table, each R independently represents an alkyl group having 1to 10 carbon atoms, and each J independently represents a hydrogen atom,an alkoxide group having 1 to 10 carbon atoms, an aryloxy group having 6to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms or ahalogen atom;

-   said neutral multidentate ligand A in formula (1) being a tridentate    ligand represented by the following formula (2) or formula (3):

wherein j, k and m independently represent an integer of 0 to 6, each D¹independently represents a divalent hydrocarbon group which may have asubstituent, each L¹ independently represents a substituent containingan element of group 14, 15, 16 or 17 of the periodic table, with theproviso that all of the three L¹s are not concurrently a substituentcontaining an element of group 14 or 17, G¹ represents a carbon orsilicon atom, and R¹ represents a hydrogen atom, an alkyl group having 1to 10 carbon atoms which may have a substituent, or an aryl group having6 to 10 carbon atoms which may have a substituent;

wherein a, b and c independently represent an integer of 0 to 6; urepresents an integer of 0 or 1; each D² independently represents adivalent hydrocarbon group which may have a substituent; each L²independently represents a substituent containing an element of group14, 15, 16 or 17 of the periodic table, with the proviso that all of thethree L²s are not concurrently a substituent containing an element ofgroup 14 or 17, G²represents a nitrogen or phosphorus atom when u is 0,or a phosphorus atom when u is 1, and R² represents an oxygen or sulfuratom. Water, acidic protons, or both may be abated from the catalyst ora component thereof prior to or during preparation of the catalyst.

In an embodiment, a catalyst for trimerization of ethylene comprises:

(i) an organometallic complex having a neutral multidentate ligandhaving a tripod structure, represented by the following formula (1):

AMQ_(n)   (1)

wherein A is a neutral multidentate ligand having a tripod structure, Mis a transition metal atom of group 3 to group 10 of the periodic table,each Q is independently selected from the group consisting of a hydrogenatom, a halogen atom, a straight chain or branched alkyl group having 1to 10 carbon atoms which may have a substituent, an aryl group having 6to 10 carbon atoms which may have a substituent, and n is an integerequal to a formal oxidation valence of M,

(ii) an alkylaluminoxane, and

(iii) an alkyl group-containing compound represented by the followingformula (4):

R_(p)EJ_(q)   (4)

wherein p and q are numbers satisfying the formulae: 0<p≦3 and 0≦q<3,provided that (P+q) is in the range of 1 to 3, E represents an atom,other than a hydrogen atom, of group 1, 2, 3, 11, 12 or 13 of theperiodic table, each R independently represents an alkyl group having 1to 10 carbon atoms, and each J independently represents a hydrogen atom,an alkoxide group having 1 to 10 carbon atoms, an aryloxy group having 6to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms or ahalogen atom;

-   said neutral multidentate ligand A in formula (1) being a tridentate    ligand represented by the following formula (2) or formula (3):

wherein j, k and m independently represent an integer of 0 to 6, each D¹independently represents a divalent hydrocarbon group which may have asubstituent, each L¹ independently represents a substituent containingan element of group 14, 15, 16 or 17 of the periodic table, with theproviso that all of the three L¹s are not concurrently a substituentcontaining an element of group 14 or 17, G¹ represents a carbon orsilicon atom, and R¹ represents a hydrogen atom, an alkyl group having 1to 10 carbon atoms which may have a substituent, or an aryl group having6 to 10 carbon atoms which may have a substituent;

wherein a, b and c independently represent an integer of 0 to 6; urepresents an integer of 0 or 1; each D² independently represents adivalent hydrocarbon group which may have a substituent; each L²independently represents a substituent containing an element of group14, 15, 16 or 17 of the periodic table, with the proviso that all of thethree L²s are not concurrently a substituent containing an element ofgroup 14 or 17, G² represents a nitrogen or phosphorus atom when u is 0,or a phosphorus atom when u is 1, and R² represents an oxygen or sulfuratom. Water, acidic protons, or both may be abated from the catalyst ora component thereof prior to or during preparation of the catalyst.

In an embodiment, a catalyst for trimerization of ethylene comprises:

(i) an organometallic complex having a neutral multidentate ligandhaving a tripod structure, represented by the following formula (1):

AMQ_(n)   (1)

wherein A is a neutral multidentate ligand having a tripod structure, Mis a transition metal atom of group 3 to group 10 of the periodic table,each Q is independently selected from the group consisting of a hydrogenatom, a halogen atom, a straight chain or branched alkyl group having 1to 10 carbon atoms which may have a substituent, an aryl group having 6to 10 carbon atoms which may have a substituent, and n is an integerequal to a formal oxidation valence of M,

(ii) an alkylaluminoxane, and

(iii) at least one compound selected from the group consisting of anamine compound and an amide compound;

said neutral multidentate ligand A in formula (1) being a tridentateligand represented by the following formula (2) or formula (3):

wherein j, k and m independently represent an integer of 0 to 6, each D¹independently represents a divalent hydrocarbon group which may have asubstituent, each L¹ independently represents a substituent containingan element of group 14, 15, 16 or 17 of the periodic table, with theproviso that all of the three L¹s are not concurrently a substituentcontaining an element of group 14 or 17, G¹ represents a carbon orsilicon atom, and R¹ represents a hydrogen atom, an alkyl group having 1to 10 carbon atoms which may have a substituent, or an aryl group having6 to 10 carbon atoms which may have a substituent;

wherein a, b and c independently represent an integer of 0 to 6; urepresents an integer of 0 or 1; each D² independently represents adivalent hydrocarbon group which may have a substituent; each L²independently represents a substituent containing an element of group14, 15, 16 or 17 of the periodic table, with the proviso that all of thethree L^(e)s are not concurrently a substituent containing an element ofgroup 14 or 17, G² represents a nitrogen or phosphorus atom when u is 0,or a phosphorus atom when u is 1, and R² represents an oxygen or sulfuratom. Water, acidic protons, or both may be abated from the catalyst ora component thereof prior to or during preparation of the catalyst.

In an embodiment, a catalyst for trimerization of ethylene comprises:

(i) an organometallic complex having a neutral multidentate ligandhaving a tripod structure, represented by the following formula (1):

AMQ_(n)   (1)

wherein A is a neutral multidentate ligand having a tripod structure, Mis a transition metal atom of group 3 to group 10 of the periodic table,each Q is independently selected from the group consisting of a hydrogenatom, a halogen atom, a straight chain or branched alkyl group having 1to 10 carbon atoms which may have a substituent, an aryl group having 6to 10 carbon atoms which may have a substituent, and n is an integerequal to a formal oxidation valence of M,

(ii) an alkylaluminoxane,

(iii) at least one compound selected from the group consisting of anamine compound and an amide compound, and

(iv) an alkyl group-containing compound represented by the followingformula (4):

R_(p)EJ_(q)   (4)

wherein p and q are numbers satisfying the formulae: 0<p≦3 and 0≦q<3,provided that (P+q) is in the range of 1 to 3, E represents an atom,other than a hydrogen atom, of group 1, 2, 3, 11, 12 or 13 of theperiodic table, each R independently represents an alkyl group having 1to 10 carbon atoms, and each J independently represents a hydrogen atom,an alkoxide group having 1 to 10 carbon atoms, an aryloxy group having 6to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms or ahalogen atom;

-   said neutral multidentate ligand A in formula (1) being a tridentate    ligand represented by the following formula (2) or formula (3):

wherein j, k and m independently represent an integer of 0 to 6, each D¹independently represents a divalent hydrocarbon group which may have asubstituent, each L¹ independently represents a substituent containingan element of group 14, 15, 16 or 17 of the periodic table, with theproviso that all of the three L¹s are not concurrently a substituentcontaining an element of group 14 or 17, G¹ represents a carbon orsilicon atom, and R¹ represents a hydrogen atom, an alkyl group having 1to 10 carbon atoms which may have a substituent, or an aryl group having6 to 10 carbon atoms which may have a substituent;

wherein a, b and c independently represent an integer of 0 to 6; urepresents an integer of 0 or 1; each D² independently represents adivalent hydrocarbon group which may have a substituent; each L²independently represents a substituent containing an element of group14, 15, 16 or 17 of the periodic table, with the proviso that all of thethree L²s are not concurrently a substituent containing an element ofgroup 14 or 17, G²represents a nitrogen or phosphorus atom when u is 0,or a phosphorus atom when u is 1, and R² represents an oxygen or sulfuratom. Water, acidic protons, or both may be abated from the catalyst ora component thereof prior to or during preparation of the catalyst.

In an embodiment, an olefin oligomerization catalyst system incorporatesa halogen source into a pyrrole ligand as disclosed in WO 01/83447, andwater, acidic protons, or both may be abated from the catalyst system ora component thereof prior to or during preparation of the catalyst. Inan embodiment, water, acidic protons, or both are abated from a catalystcomponent comprising a halopyrrole ligand. The catalyst system maycomprise a chromium source, a metal alkyl, and the halopyrrole ligandand may be utilized for producing 1-hexene by trimerizing ethylene.

In an embodiment, an olefin oligomerization catalyst system incorporatesa mixed heteroatomic ligand with at least three heteroatoms, of which atleast one heteroatom is sulfur and at least 2 heteroatoms are not thesame, as disclosed in WO 03/053890, and water, acidic protons, or bothmay be abated from the catalyst system or a component thereof prior toor during preparation of the catalyst. In an embodiment, water, acidicprotons, or both are abated from the catalyst system or a catalystcomponent comprising a multidentate mixed heteroatomic ligand, whichincludes at least three heteroatoms of which at least one is a sulfuratom. The catalyst system may comprise a chromium source, a metal alkyl,an aluminoxane, and the multidentate mixed heteroatomic ligand and maybe utilized for producing 1-hexene by trimerizing ethylene.

In an embodiment, water, acidic protons, or both may be abated from theligand and the ligand may be comprised of the following ligand types:

(a) R¹A(R²BR³)(R⁴CR⁵) wherein R¹, R³ and R⁵ may be hydrogen orindependently be selected from the groups consisting of alkyl, aryl,aryloxy, halogen, nitro, alkoxycarbonyl, carbonyloxy, alkoxy,aminocarbonyl, carbonylamino, dialkylamino, or derivatives thereof, oraryl substituted with any of these substituents; R² and R⁴ may be thesame or different and are C₁ to about C₁₅ hydrocarbyls; A is nitrogen orphosphorous; and B and C are sulfur; and

(b) R¹A(R²BR³R⁴)(R⁵CR⁶) wherein R¹, R3¹, R⁴, and R⁶ may be hydrogen orindependently be selected from the groups consisting of alkyl, aryl,aryloxy, halogen, nitro, alkoxycarbonyl, carbonyloxy, alkoxy,aminocarbonyl, carbonylamino, dialkylamino, or derivatives thereof, oraryl substituted with any of these substituents; R² and R⁵ may be thesame or different and are C₁ to about C₁₅ hydrocarbyls; A and B areindividually nitrogen or phosphorous; and C is sulfur; and

(c) A(R¹BR²R³)(R⁴CR⁵) wherein R², R³, and R⁵ may be hydrogen orindependently be selected from the groups consisting of alkyl, aryl,aryloxy, halogen, nitro, alkoxycarbonyl, carbonyloxy, alkoxy,aminocarbonyl, carbonylamino, dialkylamino, or derivatives thereof, oraryl substituted with any of these substituents; R¹ and R⁴ may be thesame or different and are C₁ to about C₁₅ hydrocarbyls; B is nitrogen orphosphorous; and A and C are sulfur; and

(d) A(R¹BR²R³)(R⁴CR⁵R⁶) wherein R², R³, R⁵, and R⁶ may be hydrogen orindependently be selected from the groups consisting of alkyl, aryl,aryloxy, halogen, nitro, alkoxycarbonyl, carbonyloxy, alkoxy,aminocarbonyl, carbonylamino, dialkylamino, or derivatives thereof, oraryl substituted with any of these substituents; R¹ and R⁴ may be thesame or different and are C₁ to about C₁₅ hydrocarbyls; B and C areindividually nitrogen or phosphorous; and A is sulfur.

In an embodiment the ligand may comprisebis(2-ethylsulfanyl-ethyl)-amine, bis-(2-methylsulfanyl-ethyl)-amine,bis-(2butylsulfanyl-ethyl)-amine,bis-(2-decylsulfanyl-ethyl)-amine,bis-(2butylsulfanyl-ethyl)-amine,bis-(2-decylsulfanyl-ethyl)-amine, bis-(ethylsulfanylmethyl)-amine,bis-(2-ethylsulfanyl-phenyl)-amine,bis-(2-ethylsulfanyl-ethyl)phosphine,bis-(2-ethylsulfanyl-ethyl)-ethylphosphine,bis-(2-ethylsulfanylethyl)-phenylphosphine,N-methylbis-(2-ethylsulfanyl-ethyl)-amine,(2ethylsulfanyl-ethyl)(3-ethylsulfanyl-propyl)-amine,(2-ethylsulfanyl-ethyl) (2diethylphosphino-ethyl)-amine,(2-ethylsulfanyl-ethyl)(2-diethylphosphinoethyl)-sulfide,(2-ethylsulfanyl-ethyl)(2-diethylamino-ethyl)-amine and(ethylsulfanyl-ethyl)(2-diethylamino-ethyl)-sulfide,(2-ethylsulfanyl-ethyl)(2diethylphosphino-ethyl)-phosphine,(2-ethylsulfanyl-ethyl)(2-diethylaminoethyl)-ethylphosphine,bis-(2-diethylphosphino-ethyl)-sulfide,bis-(2diethylamino-ethyl)-sulfide,(2-diethylphosphino-ethyl)(2-diethylamino-ethyl)sulfide and derivativesthereof, wherein water, acidic protons, or both may be abated from theligand.

In an embodiment, an olefin oligomerization catalyst system incorporatesa mixed heteroatomic ligand with at least three heteroatoms, of which atleast heteroatom is nitrogen and at least two heteroatoms are not thesame, as disclosed in WO 03/053891, and water, acidic protons, or bothmay be abated from the catalyst system or a component thereof prior toor during preparation of the catalyst. In an embodiment, the ligand maybe a multidentate mixed heteroatomic ligand for an oligomerization ofolefins catalyst, which ligand includes at least three heteroatoms. Atleast one heteroatom may be nitrogen and at least two heteroatoms maynot be the same. The ligand may contain, in addition to nitrogen, atleast one phosphorous heteroatom. In an embodiment, the ligand may beselected such that none of the non-carbon based heteroatoms are directlybonded to any of the other non-carbon based heteroatoms. In anembodiment, the ligand may not include a sulfur heteroatom. In anembodiment, water, acidic protons, or both may be abated from a ligandhaving the structure R¹A(R²BR³R⁴)(R⁵CR⁶R⁷) wherein R¹, R³, R⁴, R⁶ and R⁷may be hydrogen or independently be selected from the groups consistingof alkyl, aryl, aryloxy, halogen, nitro, alkoxycarbonyl, carbonyloxy,alkoxy, aminocarbonyl, carbonylamino, dialkylamino, or derivativesthereof, or aryl substituted with any of these substituents; R² and R⁵are the same or different and are C₁ to about C₁₅ hydrocarbyls; and atleast A, B or C is nitrogen with the remainder of A, B and C beingindividually nitrogen or phosphorous.

In an embodiment the ligand may comprisebis-(2-diethylphosphino-ethyl)-amine,bis-(diethylphosphino-methyl)-amine,bis-(2-diethylphosphino-phenyl)-amine,N-methylbis-(2-diethylphosphino-ethyl)-amine,bis-(2-diphenylphosphino-ethyl)-amine,(2-diethylphosphino-ethyl)(3-diethylphosphino-propyl)-amine,bis-(2-dicyclohexylphosphino-ethyl)-amine,N-benzylbis-(2-diethylphosphino-ethyl)-amine,N-methyl-(2-diethylphosphino-ethyl)(3-diethylphosphino-propyl)-amine,(2-diethylphosphinoethyl)(2-diethylamino-ethyl)-amine,N-methyl-(2-diethylphosphino-ethyl)(2-diethylamino-ethyl)-amine andbis-(2-diethylamino-ethyl)ethylphosphine. A suitable multidentate mixedheteroatomic ligand is bis-(2-diethylphosphino-ethyl)-amine andderivatives thereof, wherein water, acidic protons, or both may beabated from the ligand.

In an embodiment, a nitrogen-containing compound may be contacted withthe metal alkyl prior to contacting the metal alkyl with thechromium-containing compound, the pyrrole-containing compound, thehalide-containing compound, the solvent, or combinations thereof, tomake a catalyst for use in oligomerizing an olefin. Typically,preparation of catalyst can result in undesirable reaction products ofmetal alkyls, e.g., aluminum alkyls, with water impurities. Waterpresent in the catalyst components at the time they are added to themetal alkyl compound may be a source of precipitates that can lead topolymer formation in the oligomerization reaction. Such precipitates maybe abated by the addition of a nitrogen compound to the metal alkyl,thereby enhancing the solubility of the undesirable reaction productsand preventing them from precipitating out, and further minimizingpolymer production in the oligomerization reaction.

The nitrogen-compound may be comprised of amines, pyrroles, pyridines,substituted pyrroles such as indoles, di and tri nitrogen heterocycles,or combinations thereof. In an embodiment, the nitrogen-compound may be2,5-dimethylpyrrole, which in this case the nitrogen compound can servein two different functions: one, in the formation of the active site inthe catalyst system; and two, in preventing the precipitation of theproduct of the water and metal alkyl reaction (as a solubilityenhancer). In an embodiment, the nitrogen-containing compound istributyl amine. In an embodiment, the final catalyst product iscomprised of from about 0.01 to about 10 moles nitrogen per mole metal;alternatively the final catalyst product is comprised of from about 0.05to about 5 moles nitrogen to mole metal; or alternatively the finalcatalyst product is comprised of from about 0.1 to about 0.5 molesnitrogen to mole metal.

In an embodiment for making a catalyst comprising a chromium-containingcompound, a pyrrole-containing compound, a metal alkyl, ahalide-containing compound, and optionally a solvent for use inoligomerizing an olefin, the chromium-containing compound, thepyrrole-containing compound, and the metal alkyl may be simultaneouslycontacted. In an embodiment the simultaneous contact of the catalystcomponents occur via addition to a single contact zone. The simultaneouscontacting may occur over a period of time of from about 1 minute toabout 12 hours; alternatively from about 1 minute to about 6 hours; oralternatively from about 1 minute to about 3 hours. In an embodiment,the simultaneous contacting may occur over a period of less than orequal to about 120 minutes to form a catalyst product. In an embodiment,one or more of the catalyst components may be fed to the contact zone atmass flow rates of from about 0.1 Kg/hr to about 500 Kgs/hr,alternatively from about 5 Kg/hr to about 250 Kgs/hr; alternatively fromabout 10 Kg/hr to about 150 Kgs/hr; alternatively from about 0.1 Kg/hrto about 100 Kgs/hr; alternatively from about 0.1 Kg/hr to 50 Kgs/hr;alternatively from about 0.5 Kg/hr to 25 Kgs/hr; or alternatively fromabout 1.0 Kg/hr to 10 Kgs/hr. Such mass flow rates may also be employedwith other embodiments described herein. In an embodiment, thesimultaneous contacting is performed in a continuous process (whereinthe period of time may be an extended period of time), or alternativelyin a batch process. In an embodiment, the metal alkyl may be in asolution comprising a non-metal halide and a metal alkyl, a metal alkylhalide, a metal halide and a metal alkyl, or combinations thereof. In anembodiment, the halide-containing compound may also be simultaneouslycontacted with the chromium-containing compound, the pyrrole-containingcompound, and the metal alkyl, for example by simultaneous addition tothe hydrocarbon solvent.

In an embodiment as shown in FIG. 4A, the composition comprising thechromium-containing compound may be fed into contact zone 1100 via line1110, the composition comprising the pyrrole-containing compound may befed into contact zone 1100 via line 1120, the composition comprising themetal alkyl may be fed into contact zone 1100 via line 1115, and thecomposition comprising the halide-containing compound may be fed intocontact zone 1100 via line 1180, all compositions being fed into contactzone 1100 simultaneously over a period of time. In an embodiment asshown in FIG. 4B, the composition comprising the chromium-containingcompound may be fed into contact zone 1100 via line 1110, thecomposition comprising the pyrrole-containing compound may be fed intocontact zone 1100 via line 1120, the compositions comprising the metalalkyl and the halide-containing compound may be pre-contacted and fedinto contact zone 1100 via line 1117, the final compositions being fedinto contact zone 1100 simultaneously over a period of time. In anembodiment as shown in FIG. 4C, the compositions comprising thechromium-containing compound and the pyrrole-containing compound may bepre-contacted and fed into contact zone 1100 via line 1122, thecomposition comprising the metal alkyl may be fed into contact zone 1100via line 1115, and the compositions comprising the halide-containingcompound may be fed into contact zone 1100 via line 1180, the finalcompositions being fed into contact zone 1100 simultaneously over aperiod of time. In an embodiment as shown in FIG. 4D, the compositionscomprising the chromium-containing compound and the pyrrole-containingcompound may be pre-contacted and fed into contact zone 1100 via line1122 and the compositions comprising the metal alkyl and thehalide-containing compound may be pre-contacted and fed into contactzone 1100 via line 1117, the final compositions being fed into contactzone 1100 simultaneously over a period of time. In the embodiments shownin FIGS. 4A-4D, a hydrocarbon solvent may be placed in contact zone 1100before, after, or concurrently with addition of the various catalystcomponents. Contact zone 1100 may comprise a single vessel, for examplea storage tank, tote, container, mixing vessel, etc. A catalyst productmay be withdrawn from contact zone 1100 via line 1170 and optionallyfiltered (filter not shown). In the embodiments shown in FIGS. 4A-4D,the addition of the composition comprising the pyrrole-containingcompound and the composition comprising the chromium-containing compoundmay be made in constant or varying Py:Cr ratios as disclosed previously.Additionally, the water, acidic protons, or both abatement embodimentsset forth in FIGS. 2A-2D and 3A-3B may be combined with the simultaneousaddition embodiments of FIGS. 4A-4D.

In an embodiment for making a catalyst comprising a chromium-containingcompound, a pyrrole-containing compound, a metal alkyl, ahalide-containing compound, and optionally a solvent for use inoligomerizing an olefin, the compositions comprising thechromium-containing compound, the pyrrole-containing compound, the metalalkyl, optionally the halide-containing compound, or combinationsthereof may be contacted with a previously prepared oligomerizationcatalyst composition. The previously prepared oligomerization catalystsolution may comprise the same or different chromium-containingcompound, pyrrole-containing compound, metal alkyl, andhalide-containing compound. The halide-containing compound may comprisea metal halide, a metal alkyl halide, or combinations thereof.

Any of the embodiments disclosed herein for making catalysts may becarried out wherein the new catalyst may be prepared in one or morecontact zones comprising existing, previously prepared active catalyst.For example, in the embodiments shown in FIGS. 4A-D, contact zone 1100may be a holding tank for active catalyst to be fed to anoligomerization reactor and be comprised of previously preparedoligomerization catalyst. The various catalyst compounds in lines 1110,1115, 1117, 1120, 1122, and 1180 may be simultaneously combined with thepreviously prepared oligomerization catalyst composition in contact zone1100.

In an embodiment as shown in FIG. 4E, contact zone 1200 may be a holdingtank for active catalyst to be fed to an oligomerization reactor andcomprises previously made oligomerization catalyst. Thechromium-containing compound in line 1210 may be combined with ahydrocarbon solvent in line 1250 forming a first solution in contactzone 1225. The pyrrole-containing compound in line 1220, the metal alkylin line 1215, and the optional halide-containing compound in line 1280may be combined with the hydrocarbon solvent in line 1251 forming asecond solution in contact zone 1235. The hydrocarbon solvent in line1250 may be the same or different hydrocarbon solvent in line 1251. Thefirst solution in contact zone 1225 and the second solution in contactzone 1235 may then be contacted (e.g., simultaneously or sequentially,including a plurality of iterative addition sequences) with thepreviously made oligomerization catalyst composition in contact zone1200 via lines 1216 and 1218, respectively, to make the new catalystcomposition. Optionally, a mixer may be disposed in contact zone 1200 tothoroughly mix the new and existing catalyst components. Again, thecontacting of the composition comprising the pyrrole-containing compoundand the composition comprising the chromium-containing compound may bemade in constant or varying Py:Cr ratios as disclosed previously.Additionally, the water, acidic protons, or both abatement embodimentsset forth in FIGS. 2A-2D and 3A-3B may be combined with the simultaneousaddition embodiment of FIG. 4E.

Contacting of the catalyst components can be done under any conditionssufficient to thoroughly contact the components. Typically, contactingis performed in an inert atmosphere, such as, for example, nitrogenand/or argon. The reaction temperature for the disclosed methods ofmaking a catalyst for use in oligomerizing an olefin can be anytemperature. For ease of operation, ambient temperature may be employed.In order to effectuate a more efficient reaction, temperatures whichmaintain the reaction mixture in a liquid state are desirable. In anembodiment, reaction temperature is maintained at less than about 120°C.; alternatively less than about 100° C.; alternatively less than about75° C.; alternatively less than about 50° C.; or alternatively less thanabout 25° C. when contacting the compositions comprising thechromium-containing compound, the pyrrole-containing compound, the metalalkyl, the halide-containing compound, or combinations thereof to makethe catalyst. The preparation of the catalyst system at a lowtemperature may increase catalyst activity and reduce levels ofundesirable co-product polymer.

The reaction pressure for the disclosed methods of making a catalyst foruse in oligomerizing an olefin can be any pressure which does notadversely effect the reaction. Generally, pressures within the range offrom about atmospheric pressure to about three atmospheres areacceptable. For ease of operation atmospheric pressure may be employed.

The reaction time for the disclosed methods of making a catalyst for usein oligomerizing an olefin can be any amount of time that can reactsubstantially all reactants (i.e., catalyst components). Depending onthe reactants, as well as the reaction temperature and pressure,reaction time can vary. Usually, times of less than about 1 day can besufficient, for example from about 1 minute to about 12 hours. In anembodiment, reaction time is from about 1 minute to about 6 hours,alternatively from about 1 minute to about 3 hours. Longer times usuallyprovide no additional benefit and shorter times may not allow sufficienttime for complete reaction.

The resultant olefin oligomerization catalyst system prepared asdescribed above in any of the embodiments can be collected and keptunder a dry, inert atmosphere to maintain chemical stability andreactivity. In an embodiment, it may be desirable to contact thecatalyst with the olefin within about 1000 hours of preparation of thecatalyst; alternatively the catalyst may be contacted with the olefinwithin about 800 hours of preparation of the catalyst; alternatively thecatalyst may be contacted with the olefin within about 600 hours ofpreparation of the catalyst; alternatively the catalyst may be contactedwith the olefin within about 400 hours of preparation of the catalyst;or alternatively the catalyst may be contacted with the olefin withinabout 200 hours of preparation of the catalyst. In an embodiment, theolefin oligomerization catalyst comprising the chromium-containingcompound, the pyrrole-containing compound, the metal alkyl, thehalide-containing compound, and optionally the solvent may product aproduct (e.g., hexane) having a purity of at least 99.4 at a time withinabout 200 hours after preparation of the catalyst; alternatively theproduct may have a purity of at least about 99.3 at a time within about400 hours after preparation of the catalyst; alternatively the productmay have a purity of at least about 99.1 at a time within about 600hours after preparation of the catalyst; alternatively the product mayhave a purity of at least about 98.8 at a time within about 800 hoursafter preparation of the catalyst; or alternatively the product may havea purity of less than about 98.8 at a time greater than about 900 hoursafter preparation catalyst.

The chromium-containing compound may be one or more organic or inorganicchromium compounds, with a chromium oxidation state of from about 0 toabout 6. As used in this disclosure, chromium metal may be included inthis definition of a chromium compound. Generally, thechromium-containing compound will have a formula of CrX_(n), wherein Xcan be the same or different and can be any organic or inorganicradical, and n may be an integer from 0 to 6. Suitable organic radicalscan have from about 1 to about 20 carbon atoms per radical, and areselected from alkyl, alkoxy, ester, ketone, amino radicals, orcombinations thereof. The organic radicals can be straight-chained orbranched, cyclic or acyclic, aromatic or aliphatic, and can be made ofmixed aliphatic, aromatic, and/or cycloaliphatic groups. Suitableinorganic radicals include, but are not limited to halides, sulfates,oxides, or combinations thereof.

The chromium-containing compound may be a chromium (II) compound,chromium (III) compound, or combinations thereof. Suitable chromium(III) compounds include, but are not limited to, chromium carboxylates,chromium naphthenates, chromium halides, chromium pyrrolides, chromiumbenzoates, chromium dionates, or combinations thereof. Specific chromium(III) compounds include, but are not limited to, chromium (III)isooctanoate, chromium (III) 2,2,6,6-tetramethylheptanedionate, chromium(III) naphthenate, chromium (III) chloride, chromium (III)tris(2-ethylhexanoate), chromic bromide, chromic chloride, chromicfluoride, chromium (III) oxy-2-ethylhexanoate, chromium (III)dichloroethylhexanoate, chromium (III) acetylacetonate, chromium (III)acetate, chromium (III) butyrate, chromium (III) neopentanoate, chromium(III) laurate, chromium (III) stearate, chromium (III) oxalate, chromium(III) benzoate, chromium (III) pyrrolide(s), or combinations thereof.Suitable chromium (II) compounds include, but are not limited to,chromous fluoride, chromous chloride, chromous bromide, chromous iodide,chromium (II) bis(2-ethylhexanoate), chromium (II) acetate, chromium(II) butyrate, chromium (II) neopentanoate, chromium (II) laurate,chromium (II) stearate, chromium (II) oxalate, chromium (II) benzoate,chromium (II) pyrrolide(s), or combinations thereof. In an embodiment,the chromium-containing compound may be chromium (III) 2-ethylhexanoate.

In an embodiment, the monomeric chromium content and the residual(excess) radicals are optimized. This value is designated by the ratiomoles Cr:((moles ligand×number of coordination equivalents of theligand/mole of ligand)/Cr oxidation number). In an embodiment the ratiomoles Cr:((moles ligand×number of coordination equivalents of theligand/mole of ligand)/Cr oxidation number) is from about 0.9:1 to about1.1:1, alternatively from about 0.94:1 to about 1.08:1, alternativelyfrom about 0.97:1 to about 1.05:1.

In an embodiment the chromium compound is chromium (III)2-ethylhexanoate. The weight percent chromium is in the range from about10.3 wt % to 12.8 wt %; alternatively from 10.4 wt % to 11.8 wt %;alternatively from 10.5 wt % to 11.2 wt %. The amount of chromiumoligomers is low such that the chromium compound demonstrates methanolsolubility. The amount of free acid is below 50 weight percent;alternatively below 30 weight percent; alternatively below 20 weightpercent. Particulates, insoluble in hexane, are below 1 weight percent;alternatively below 0.5 weight percent; alternatively below 0.2 weightpercent. Water content is below 1 weight percent; alternatively below0.5 weight percent; alternatively below 0.2 weight percent.

The pyrrole-containing compound can be any pyrrole-containing compoundthat will react with a chromium salt to form a chromium pyrrolidecomplex. The pyrrole-containing compound includes hydrogen pyrrolide,e.g., pyrrole (C₄H₅N), derivatives of pyrrole, as well as metalpyrrolide complexes, alkali metal pyrrolides, salts of alkali metalpyrrolides, or combinations thereof. A pyrrolide (or a pyrrole) can beany compound comprising a 5-membered, nitrogen-containing heterocycle,such as pyrrole, derivatives of pyrrole, substituted pyrrole, andmixtures thereof. Broadly, the pyrrole-containing compound can bepyrrole, any heteroleptic or homoleptic metal complex or salt containinga pyrrolide radical or ligand, or combinations thereof.

Generally, the pyrrole-containing compound will have from about 4 toabout 20 carbon atoms per molecule. Pyrrolides (or pyrroles) includehydrogen pyrrolide (pyrrole), derivatives of pyrrole, substitutedpyrrolides (or pyrroles), lithium pyrrolide, sodium pyrrolide, potassiumpyrrolide, cesium pyrrolide, the salts of substituted pyrrolides, orcombinations thereof. Examples of substituted pyrrolides (or pyrroles)include, but are not limited to, pyrrole-2-carboxylic acid,2-acetylpyrrole, pyrrole-2-carboxaldehyde, tetrahydroindole,2,5-dimethylpyrrole, 2,4-dimethyl-3-ethylpyrrole,3-acetyl-2,4-dimethylpyrrole,ethyl-2,4-dimethyl-5-(ethoxycarbonyl)-3-pyrrole-propionate,ethyl-3,5-dimethyl-2-pyrrole-carboxylate

In an embodiment the pyrrole containing compound is 2,5-dimethylpyrrole.The content of 2,5-dimethylpyrrole is greater than 98 weight percent;alternatively greater than 99.0 weight percent; alternatively greaterthan 99.5 weight percent. The water content of the pyrrole containingcompound is below 1 weight percent; alternatively below 0.5 weightpercent; alternatively below 0.01 weight percent. The color of thepyrrole containing compound (Platinum-Cobalt Number) is below 200;alternatively below 120; alternatively below 80.

In an embodiment, the pyrrole-containing compound used in anoligomerization catalyst system comprises a dimeric pyrrole compound,for example one or more compounds represented by the following generalstructures:

wherein, each R¹-R⁶ may independently be H, or a C₁-C₂₀ aromatic group,or any two vicinal to each other, taken together with the carbon atom towhich they are bonded may form an aromatic or non-aromatic ring. Y is astructural bridge having 1 to 20 carbon atoms and may include linear,branched, or cyclic paraffinic or aromatic or contain cyclic paraffinicor aromatic structures and may include hetero atoms such as oxygen orsulfur in the form of linear, branched, or cyclic ether, silyl, sulfide,sulfone, sulfoxide functionality.

In an embodiment shown as Structure (I), R¹, R³, R⁴, and R⁶ are methylgroup, R² and R⁵ are hydrogens, and Y═(CH₂)_(n) wherein n=1-10. In anembodiment shown as Structure (II), R¹ and R⁶ are methyl groups, R²-R⁵are hydrogens, and Y═(CH₂)_(n) wherein n=1-10. In embodiment shown asStructure (III), R¹, R³, and R⁵ are methyl groups, R², R⁴, and R⁶ arehydrogen, and Y═(CH₂)_(n) wherein n=1-10.

Use of the dimeric pyrroles may produce a catalyst system with activityand selectivity to a desired oligomerized product, such as, for example,the trimerization of ethylene to 1-hexene, as well as low polymerproduction.

The metal alkyl, sometimes referred to as an activating compound, may bea heteroleptic or homoleptic metal alkyl compound of any of the metalsaluminum, boron, lithium, magnesium, or zinc. The metal alkyl may be ametal alkyl halide such as DEAC; a non-halide metal alkyl such as TEA;or combinations thereof. One or more metal alkyls can be used. Theligand(s) on the metal can be aliphatic, aromatic, or combinationsthereof. For example, the ligand(s) may be any saturated or unsaturatedaliphatic radical. The metal alkyl may be a compound that can beconsidered both a Lewis acid and a metal alkyl. As used in thisdisclosure, a Lewis acid may be defined as any compound that may be anelectron acceptor. Activating compounds which are both a metal alkyl anda Lewis acid include alkylaluminum compounds, alkylmagnesium, alkylzinc,alkyllithium compounds, or combinations thereof. The metal alkyl canhave any number of carbon atoms. However, due to commercial availabilityand ease of use, the metal alkyl will usually comprise less than about70 carbon atoms per metal alkyl molecule and alternatively less thanabout 20 carbon atoms per molecule. In an embodiment, the metal alkylsare non-hydrolyzed, i.e., not pre-contacted with water, such asalkylaluminum compounds, derivatives of alkylaluminum compounds,halogenated alkylaluminum compounds, and mixtures thereof for improvedproduct selectivity, as well as improved catalyst system reactivity,activity, productivity, or combinations thereof. In an embodiment themetal alkyl may be non-halide metal alkyl, a metal alkyl halide, anon-hydrolyzed alkylaluminum compound, a hydrolyzed alkylalumimumcompound, or combinations thereof.

Suitable non-halide metal alkyls include, but are not limited to,alkylaluminum compounds, alkyl boron compounds, alklymagnesiumcompounds, alkylzinc compounds, alkyllithium compounds, or combinationsthereof. Suitable non-halide metal alkyls include, but are not limitedto, n-butyllithium, s-butyllithium, t-butyllithium, diethylmagnesium,dibutylmagnesium, diethylzinc, triethylaluminum, trimethylaluminum,tripropylaluminum, tributylaluminum, triisobutylaluminum,tri-n-hexylaluminum, tri-n-octylaluminum, diethylaluminum ethoxide,diethylaluminum phenoxide, and mixtures thereof. Suitable metal alkylhalide compounds include, but are not limited to, ethylaluminumdichloride, diethylaluminum chloride, diethylaluminum bromide,diethylaluminum sesquichloride, diisobutylaluminum chloride,ethylaluminum sesquichloride, diethylaluminum bromide, diethylaluminumiodide, ethylaluminumethoxychloride, and mixtures thereof. In anembodiment, the alkylaluminum compound may be triethylaluminum.

When a trimerization catalyst system may be the desired product, themetal alkyl may be at least one non-hydrolyzed alkylaluminum compound,expressed by the general formulae AlR₃, AlR₂X, AlRX₂, AlR₂OR, AlRXOR,Al₂R₃X₃, or combinations thereof, wherein R may be an alkyl group and Xmay be a halogen atom. Suitable compounds include, but are not limitedto, trimethylaluminum, triethylaluminum, tripropylaluminum,tri-n-butylaluminum, tri-isobutylaluminum, tri-n-hexylaluminum,tri-n-octylaluminum, diethylaluminumchloride, diethylaluminumbromide,diethylaluminumethoxide, diethylaluminum phenoxide,ethylaluminumethoxychloride, ethylaluminum dichloride, diethylaluminumchloride, diethylaluminum bromide, ethylaluminum sesquichloride, orcombinations thereof. In an embodiment, the activating compound for anoligomerization catalyst system may be a trialkylaluminum compound,AlR₃, for example triethylaluminum. Additionally, hydrolyzedalkylaluminum compounds, aluminoxanes, may be used. Aluminoxanes can beprepared as known in the art by reacting water or water containingmaterials with trialkylaluminium compounds. Suitable aluminoxanes areprepared from trialkylaluminium compounds such as trimethylaluminium,triethylaluminium, tripropylaluminium, tributylaluminium,trlisobutylaluminium, trihexylaluminium or the like, and mixturesthereof. Mixtures of different aluminoxanes may also be used. Suitablehydrolyzed alkylaluminum compounds include, but are not limited tomethylaluminoxane, modified methylaluminoxane, and ethylaluminoxanes,and mixtures thereof.

The olefin oligomerization catalyst systems can further comprise acatalyst support. A supported chromium catalyst system can be preparedwith any support useful to support a chromium catalyst. Suitablecatalyst supports include, but are not limited to, zeolites, inorganicoxides, either alone or in combination, phosphated inorganic oxides, andmixtures thereof, for example silica, silica-alumina, alumina, fluoridedalumina, silated alumina, thoria, aluminophosphate, aluminum phosphate,phosphated silica, phosphated alumina, silica-titania, coprecipitatedsilica/titania, fluorided/silated alumina, and mixtures thereof. In anembodiment, the catalyst support, is aluminophosphate.

The solvent may be a hydrocarbon solvent, a halogenated hydrocarbonsolvent, or combinations thereof, usually having not more than 30 carbonatoms. Specific examples of the solvents may include aliphatic andalicyclic saturated hydrocarbons such as isobutane, pentane, n-hexane,hexanes, cyclohexane, n-heptane or n-octane, aliphatic and alicyclicunsaturated hydrocarbons such as 2-hexene, cyclohexene or cyclo-octene,aromatic hydrocarbons such as toluene, benzene or xylenes, othro-xylene,meta-xylene, paraxylene, chlorobenzene, halogenated hydrocarbons such ascarbon tetrachloride, chloroform, methylene chloride or chlorobenzene ordichlorobenzene, or the like. In an embodiment, the hydrocarbon solventmay be an aromatic or a halogenated aromatic compound having betweenabout 6 to about 20 carbon atoms; a saturated or unsaturated hydrocarbonhaving from about 3 to about 14 carbon atoms; a halogenated saturatedhydrocarbon having from about 1 to about 9 carbon atoms; or combinationsthereof. The solvent may be a hydrocarbon such as cyclohexane,isobutane, n-hexane, hexanes, n-heptane, heptanes, pentane, or mixturesthereof. In an embodiment the solvent is ethylbenzene. In an embodimentthe solvent is tetradecene. In an embodiment, alpha-olefins may be usedas the solvent, for example 1-hexene. In an embodiment, the solvent maycomprise normal and/or isomeric mixtures of butene, hexene, octene,decene, dodecene, tetradecene, or combinations thereof.

In an embodiment, the hydrocarbon compound used as a solvent can be anycombination of one or more aromatic or aliphatic unsaturated hydrocarboncompounds. While not wishing to be bound by theory, it may be believedthat an unsaturated hydrocarbon compound acts as more than a solvent,and can be a reactant, a stabilizing component, or both, either during,subsequent, or both, to formation of an inventive catalyst system.Suitable unsaturated hydrocarbon compounds can be any unsaturatedhydrocarbon compound that can solubilize the catalyst system. In anembodiment, aromatic compounds having from about 6 to about 20 carbonatoms per molecule as a solvent there can be used in combination withany unsaturated aliphatic hydrocarbon comprising less than about 20carbon atoms per molecule. Specific unsaturated aliphatic compoundsinclude ethylene, 1-hexene, 1,3-butadiene, and mixtures thereof. In anembodiment, the unsaturated aliphatic hydrocarbon compound may beethylene, which may be both a solvent and a reactant. Specificunsaturated aromatic hydrocarbon compounds include, but are not limitedto, toluene, benzene, ortho-xylene, metaxylene, para-xylene,ethylbenzene, xylene, mesitylene, hexamethylbenzene, and mixturesthereof.

The halide-containing compound can be any compound containing a halogen,for example organohalides (including those listed as suitable solvents);non-organohalides; metal halides (including metal alkyl halides such asthose previously described and non-alkyl metal halides such as tintetrachloride and magnesium chloride); non-metal halides; orcombinations thereof. Suitable compounds include, but are not limitedto, compounds with a general formula of R_(m)X_(n), wherein R can be anyorganic radical, inorganic radical, or both, X can be a halide, selectedfrom fluoride, chloride, bromide, iodide, or combinations thereof, and mand n each are numbers greater than 0. Where R is an organic radical, Rmay have from about 1 to about 70 carbon atoms per radical,alternatively from 1 to 20 carbon atoms per radical, for bestcompatibility and catalyst system activity. Where R is an inorganicradical, R may be selected from aluminum, silicon, germanium, hydrogen,boron, lithium, tin, gallium, indium, lead, and mixtures thereof. In anembodiment, the halide-containing compound is a chloride-containingcompound such as DEAC or organochlorides. Specific organo halidescompounds include, but are not limited to, methylene chloride,chloroform, benzylchloride chlorobenzene, carbon tetrachloride,chloroethane, 1,1-dichloroethane, 1,2-dichloroethane, tetrachloroethane,hexachloroethane, 1,4-di-bromobutane, 1-bromobutane, aryl chloride,carbon tetrabromide, bromoform, bromobenzene, iodomethane,di-iodomethane, hexafluorobenzene trichloro-acetone, hexachloro-acetone,hexachloro-cyclohexane, 1,3,5-trichloro-benzene, hexachloro-benzene,trityl chloride, or mixtures thereof. Specific non-alkyl metal halidesinclude but are not limited to silicon tetrachloride, tin (II) chloride,tin (IV) chloride, germanium tetrachloride, boron trichloride, scandiumchloride, yttrium chloride, lanthanum chloride, titanium tetrachloride,zirconium tetrachloride, hafnium tetrachloride, aluminum chloride,gallium chloride, silicon tetrachloride, tin tetrachloride, phosphorustrichloride, antimony trichloride, trityl-hexachloro-antimonate,antimony pentachloride, bismuth trichloride, boron tribromide, silicontetrabromide, aluminum fluoride, molybdenum pentachloride, tungstenhexachloride, aluminum tribromide, aluminum trichloride, or combinationsthereof. Specific metal alkyl halide compounds include, diethyl aluminumchloride, ethyl aluminum sesquichloride, ethyl aluminum dichloride,mixture of non-halide metal alkyls and metal halides,trimethyl-chlorosilane, tributyl tin chloride, dibutyl tin dichloride,or combinations thereof.

Furthermore, the chromium-containing compound, the metal alkyl, orsolvent can contain and provide a halide to the reaction mixture. Forexample, the halide source may be an alkylaluminum halide and may beused in conjunction with alkylaluminum compounds. Suitable alkylaluminumhalides include, but are not limited to, diisobutylaluminum chloride,diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminumdichloride, diethylaluminum bromide, diethylaluminum iodide, andmixtures thereof.

The amount of each reactant used to prepare an oligomerization catalystsystem can be any amount sufficient that, when combined to form thecatalyst system, oligomerization occurs upon contact with one or moreolefins. Generally, a molar excess of the metal alkyl is used. In anembodiment, expressed as a molar ratio, in terms of moles of nitrogen(N) in the pyrrole compound to moles of metal (M) in the metal alkyl,usually at least a 1:150 molar ratio is used. In an embodiment, themetal (M) is aluminum. In an embodiment, the N:M molar ratio is fromabout 1:1 to about 1:50, alternatively from about 1:1 to about 1:20, oralternatively from about 1:1 to about 1:10. Generally, the amount ofmetal alkyl/pyrrole solution used is determined based on the moles ofchromium. In an embodiment, expressed as a molar ratio, in terms ofmoles of chromium (Cr) to moles of nitrogen (N) in the pyrrole compoundto moles of metal (M) in the metal alky, i.e., Cr:N:M, the ratio of thechromium containing compound to the pyrrole-containing compound is atleast about 1:15 and the ratio of the chromium containing compound tometal alkyl is at least about 1:150 such that Cr:N:M is at least about1:15:150. In an embodiment, the Cr:N:M molar ratio is within a range ofabout 3:3:3 (also expressed as about 1:1:1) to about 1:3:100;alternatively, the Cr:N:M molar ratio is within a range of 1:3:9 to1:3:21. In an embodiment, to prepare an oligomerization catalyst system,about one mole of chromium, as the element chromium (Cr), can becontacted with about 1 to about 50 moles of pyrrole-containing compoundand about 1 to about 75 moles of aluminum, as the element, optionally inan excess of unsaturated hydrocarbon. The halide source may be presentin an amount from about 1 to about 75 moles of halide, as the element.In an embodiment, about 1 mole of chromium, calculated as the elementchromium (Cr), can be contacted with about 1 to about 15 moles ofpyrrole-containing compound; about 5 to about 40 moles of aluminum,calculated as the element aluminum (Al); and about 1 to about 30 molesof the halide-containing compound, calculated as elemental halide (X);in an excess of unsaturated hydrocarbon. In an embodiment, about onemole of chromium, as the element (Cr), may be contacted with two to fourmoles of pyrrole-containing compound; 10 to 2 moles of aluminum, as theelement (Al); and 2 to 15 moles of halide, as an element (X); in anexcess of unsaturated hydrocarbon.

The ratio of pyrrole to chromium (Py:Cr) in the final catalystcomposition recovered as product from the various embodiments disclosedherein is referred to as the final Py:Cr molar ratio. The final Py:Crmolar ratio of the catalyst may be in a range of from about 1.0:1 toabout 4.0:1; alternatively from about 1.5:1 to about 3.7:1;alternatively from about 1.5:1 to about 2.5:1; alternatively from about2.0:1 to about 3.7:1; alternatively from about 2.5:1 to about 3.5:1; oralternatively from about 2.9:1 to about 3.1:1.

The catalyst synthesis prepared in a hydrocarbon solvent may be referredto as a catalyst system solution. The resultant catalyst system, priorto introduction to any of the reactant, may have a chromiumconcentration of about less than about 50 mg Cr/ml catalyst systemsolution, for example from about 0.005 g Cr/mL catalyst system solutionto about 25 mg Cr/ml catalyst system solution, alternatively from about0.1 mg Cr/ml catalyst system solution to about 25 mg Cr/ml catalystsystem solution, alternatively from about 0.5 mg Cr/ml catalyst systemsolution to about 15 mg Cr/ml catalyst system solution, or alternativelyfrom about 1 mg Cr/ml catalyst system solution to about 15 mg Cr/mlcatalyst system solution

Catalysts prepared in accordance with the present disclosure may be usedfor the oligomerization of olefins, for example, alpha-olefins. Theoligomerization of olefins may be conducted by any suitableoligomerization methods. In an embodiment, an oligomerization catalystis contacted with one or more olefins in a reaction zone under suitablereaction conditions (e.g., temperature, pressure, etc.) to oligomerizethe olefins. Linear or branched alpha-olefins having 2 to 30 carbonatoms can be used as the olefins raw material. Specific examples of thealpha-olefins may include ethylene, propylene, 1-butene, 1-hexene,1-octene, 3-methyl-1-butene, 4-methyl-1-pentene or the like. Whenethylene is used as the alpha-olefin, it is possible to produce 1-hexeneas a trimer of ethylene with a high yield and a high selectivity.

In the description above, like parts are marked throughout thespecification and drawings with the same reference numerals,respectively. The drawing figures are not necessarily to scale. Certainfeatures of the invention may be shown exaggerated in scale or insomewhat schematic form and some details of conventional elements maynot be shown in the interest of clarity and conciseness. The presentdisclosure is susceptible to embodiments of different forms. There areshown in the drawings, and herein are described in detail, specificembodiments of the present disclosure with the understanding that thepresent disclosure is to be considered an exemplification of theprinciples of the invention, and is not intended to limit the inventionto that illustrated and described herein. It is to be fully recognizedthat the different teachings of the embodiments discussed above may beemployed separately or in any suitable combination to produce desiredresults. Specifically, the present disclosure for a method of making acatalyst by contacting of catalyst components should not be limited byany of the various embodiments described. Various embodiments set forthin the figures may be combined. For example, the water, acidic protons,or both abatement embodiments set forth in FIGS. 2A-2D and 3A-3B may becombined with the bulk addition embodiments of FIGS. 1A-1D or thesimultaneous addition embodiments of FIGS. 4A-4E. Additionally, variousembodiments for abating water may be combined in any desired number andsequence, for example azeotropic distillation followed by contact with anon-halide metal alkyl (e.g., TEA), contact with an adsorbent, or bothin any order; contact with a non-metal halide followed by contact withan adsorbent (or vice-versa); azeotropic distillation before, after, orbetween contact with a non-metal halide followed by contact with anadsorbent; etc. The water, acidic protons, or both abatement, bulkaddition, and simultaneous addition embodiments may be integrated in anydesired and operable number and sequence in other embodiments. Themethod disclosed herein is for making an oligomerization catalyst thatmay be useful in any suitable reaction such that the reaction is anoligomerization reaction. In an embodiment, the method of the presentdisclosure is for a trimerization catalyst for use in a trimerizationreaction producing 1-hexene from ethylene and the detailed descriptionabove may be focused on this embodiment but with the understanding thatthe present invention may have broader applications.

Examples

Preparation of an oligomerization catalyst having been generallydescribed, the following examples are given as particular embodiments ofthe catalyst disclosed and to demonstrate the practice and advantagesthereof. It is understood that the examples are given by way ofillustration and are not intended to limit the specification or theclaims to follow in any manner.

Various embodiments for preparing the oligomerization catalyst are shownin examples 1 through 14. In example 1, selective 1-hexene catalyst isprepared at various temperatures and chromium concentrations. In example2, selective 1-hexene catalyst is prepared by simultaneous addition ofchromium/ethylbenzene and TEA/DEAC/pyrrole/ethylbenzene to the heel ofpreviously prepared catalyst. In example 3, selective 1-hexene catalystis prepared by using a pyrrole:chromium ratio of 6:1 for the first halfof the chromium/pyrrole addition and a pyrrole:chromium ratio of 0during the second half of the chromium/pyrrole addition. In example 4,selective 1-hexene catalyst is prepared by simultaneous addition of allcatalyst components. In example 5, chromium compounds containing variousamounts of water and chromium oligomers are used in the preparation ofthe selective 1-hexene catalyst. In example 6, selective 1-hexenecatalyst is prepared by separate but simultaneous addition of thepyrrole and chromium components to a solution of TEA and DEAC. Inexample 7, selective 1-hexene catalyst is improved when a small amountof TEA is added to the chromium component and water, acidic protons, orboth are abated. In example 8, water, acidic protons, or both are abatedin the preparation of the selective 1-hexene catalyst by contacting asmall amount of TEA with the chromium/pyrrole solution. In example 9,preparation of the selective 1-hexene catalyst is made by varying thepyrrole:chromium ratio during the addition to TEA/DEAC.

In example 10, preparation of the selective 1-hexene catalyst is madeusing high initial pyrrole:chromium contact ratios when contacted withTEA/DEAC. In example 11, preparation of the selective 1-hexene catalystis made using simultaneous separate addition of catalyst components tothe heel of previously prepared catalyst. In example 12, preparation ofthe selective 1-hexene catalyst is made with the addition of a nitrogencompound to the alkylaluminum compound to solubilize products resultingfrom the reaction of water and aluminum alkyls. In example 13, water isabated when the pyrrole and chromium components are contacted to reducethe chromium component's viscosity, facilitating water removal usingmolecular sieves. In example 14, water is abated by azeotropicdistillation to remove the water from the chromium catalyst component.In example 15, the impact of the catalyst age on 1-hexene purity isdescribed. Several of the above examples also include the embodiment forthe addition of chromium and/or pyrrole to the alkyl aluminums.

In the examples below, catalyst was prepared using one of two apparatusset-ups. One set-up is a lab scale set-up for preparing catalyst insmall quantities, for example 100 ml, which are typically used forscreening purposes. The other set-up is a pilot plant scale set-uptypically designed for preparing larger quantities of catalyst, forexample 3.5 gallons, which would be suitable for use in a pilot plant.

The lab scale set-up prepares catalyst in a dry box in which theatmosphere inside the box is controlled with a helium blanket keeping itfree of oxygen and moisture, which may be detrimental to the catalystcomponents, the prepared catalysts, or both. All lab scale catalystpreparation procedures described in the examples below are performed inglassware in a dry box. Once the catalyst is prepared it is diluted withcyclohexane to the concentration desired for oligomerization reactortests. The diluted catalyst solution is then transferred into a 300 ccmetal cylinder to provide the means for transport of the catalyst to anoligomerization reactor under protected atmosphere. Note that anytransfer of components via syringes described in the examples below isdone in the dry box.

The pilot plant scale set-up prepares catalyst under a nitrogen blanketto control the atmosphere, keeping it free of oxygen and moisture. Allpilot plant scale catalyst preparation procedures described in theexamples below are performed in a 5 gallon reactor comprising a hasteloysteel autoclave. Once the catalyst is prepared it is filtered into a5-10 gallon metal cylinder. About 150 grams of the prepared catalyst isthen transferred from the large cylinder into a smaller, 300 cc, metalcylinder and transported to a helium blanketed dry box as describedabove. The prepared catalyst is transferred into glassware and isdiluted with cyclohexane to the desired concentration for testing in theoligomerization reactor. The diluted catalyst solution is thentransferred into a 300 cc metal cylinder and transported to anoligomerization reactor.

In the examples below, the prepared catalyst is tested in either a batchor a continuous oligomerization reactor. The batch oligomerizationreactor is a 1 liter autoclave that is sealed and is under a nitrogenblanket. It has a magnetic stirring device to stir the contents of thesealed container. Prepared catalyst solution transported to theoligomerization reactor in the 75 cc metal cylinder. Solvent, e.g.,cyclohexane, is charged to the oligomerization reactor, and the catalystis transferred to the reactor by connecting the cylinder to the reactorand pressurizing the cylinder with ethylene, which conveys the catalystinto the reactor. The oligomerization reactor is pressurized with 650psig of ethylene and 50 psig of hydrogen, and is operated at atemperature of about 115° C.

In some of the examples below, a continuous oligomerization reactor isused to test the prepared catalyst. The continuous oligomerization ispreformed by controlling of all the feeds to the reactor by usingseparate controls for each feed component. Hydrogen is fed to thereactor at a rate of about 0.5 L/hr, and ethylene is fed to the reactorat a rate of about 497 g/hr. The reactor is either a 1 liter or a 1gallon autoclave, depending on the desired residence time in thereactor. Reaction temperature is about 115° C., and pressure is about800 psig.

Online samples of production from the continuous oligomerization reactorwere collected via liquid sampling valves (manufactured by Valco) andfed to an online gas chromatograph (GC), a Hewlett Packard 6890, foranalysis. The productions samples were analyzed by the GC for the amountof ethylene present, hexene present, and C₆ isomers and higher oligomerspresent. From this information the selectivity, purity, and conversionwas calculated. Selectivity (1−C₆=) refers to the weight percent ofethylene converted into 1-hexene. Purity (1−C₆=/ C₆) refers to theweight percent of 1-hexene in the total of all C₆ isomers. Conversion(C₂=) refers to the weight percent of ethylene has been converted tooligomer product (e.g., hexene or decenes, etc.). Productivity refershow much 1-hexene the catalyst produced, and relates to the amount ofcatalyst is used. Productivity is quantified in units of grams of1-hexene per gram of chromium (g 1−C₆=/g Cr). In the batch processes,productivity is evaluated over a 30 minute time frame. Other evaluationsmade on the oligomerization processed catalyst examples include reactorpolymer (Rx Polymer) and total polymer. At the end of each day, thereactor was opened and cleaned. Any formed polymer inside the reactorwas collected, allowed to dry, and then weighed. This amount was thenscaled up to a commercial sized processing unit of 100,000,000pounds/year and reported as reactor polymer, quantified in pounds perhour expected in a 100,000,000 pound per year plant (Lb/Hr 100 MM/yrPlant). A filter comprising a stainless steel pad placed downstream ofthe reactor was also removed, dried and weighed at the end of each dayfor amounts of polymer. This amount of polymer was then scaled up to a100,000,000 pounds/year plant and added to the reactor polymer amountfor reporting the total polymer, quantified in pounds per hour expectedin a 100,000,000 pound per year plant (Lb/Hr 100MM/yr Plant).

To determine the presence of water of hydration in some of the samplesan infrared analysis was done using a standard IR apparatus. The IR bandfor the complexed water, e.g., about 1450 cm⁻¹, of hydration is near theband for chromium oligomers, making it difficult to distinguish the two.Therefore, in some cases a methanol solution test for precipitation ofchromium oligomers was performed to help in evaluating the onlinesamples to determine the presence of water of hydration.

Example 1

Catalyst 1-8: Catalyst was prepared by adding 14.1 lbs of dry,nitrogen-purged toluene to a 5 gallon reactor. To the toluene was added630.9 g chromium (III) 2-ethylhexanoate dissolved in 750 mL toluenefollowed by a 300 mL toluene rinse. 2,5-Dimethylpyrrole (388.9 mL) wasadded to the chromium solution in the reactor. The reactor was purgedwith nitrogen and brought to a temperature of 25° C. A mixture of 1,600g neat triethylaluminum (TEA) and 1,229 g neat diethylaluminum chloride(DEAC) was then added to the reactor followed by 0.2 lbs of toluenerinse. The temperature increased 18° C. and was returned to 25° C. withcooling. The contents of the reactor stood overnight and were thenfiltered, using a filter comprising a combination of a metal screen,filter paper, glass wool, diatomaceous earth, and another layer of glasswool. Additional catalysts were prepared in which the temperature andchromium concentration of the catalyst preparations were varied. Thecatalysts were tested for productivity in a 1 gallon continuous reactorand the results are shown in Table 1.

TABLE 1 Rx Polymer Temp Concentration Productivity (Lb/Hr Catalyst (°C.) (mg Cr/mL) (g 1-C6═/g Cr) 100 MM/yr Plant) Ratio Cr/pyrrole/TEA/DEAC(1/3/11/8) 1 25 1 43,183 0.001 2 75 1 40,010 0.083 3 25 5 45,769 0.005 475 5 44,599 0.000 Ratio Cr/pyrrole/TEA/DEAC (1/1.8/6.5/5) 5 25 1 41,9610.015 6 75 1 38,008 0.005 7 25 5 43,373 0.016 8 75 5 27,127 0.906

The examples show that catalyst productivity increased with a reductionin catalyst preparation temperature. Additionally, the examples show thebest catalyst productivity was observed in catalyst 3 and catalyst 7with 45,769 g 1−C6=/g Cr and 43,373 g 1−C6=/g Cr, respectively, whenprepared at low temperature (25° C.) and high chromium concentration (5mg Cr/mL). Low reactor polymer was also observed under the bestproductivity conditions.

Example 2

Catalyst 9-10: An ethylbenzene solution containing 2.3 g chromium (III)2-ethylhexanoate and 8.13 g ethylbenzene was prepared. A separatesolution containing 6.05 g neat triethylaluminum (TEA), 4.63 g neatdiethylaluminum chloride (DEAC), 1.37 g 2,5-dimethylpyrrole and 22.6 gethylbenzene was also prepared. These two solutions were added to 30.98g of active catalyst over a 40 minute period such that the addition timefor both solutions started and ended at the same time. The catalyst wastested in a 1 L continuous reactor and the average results of two testruns are shown in Table 2 as Catalyst 10. The average of two test runsof a standard catalyst preparation is shown in Table 2 as Catalyst 9.

TABLE 2 Total Selectivity Purity Productivity Rx Polymer PolymerCatalyst (1−C₆=) (1−C₆=) (g 1−C₆=/g Cr) (Lb/Hr 100 MM/yr Plant) 9 89.3%98.8% 82,575 0.00 13.33 10 89.1% 98.7% 82,989 0.00 7.18

The examples show that an acceptable catalyst can be prepared. Theexamples further indicate that a fewer number of tanks may be requiredto prepare catalyst.

Example 3

Catalyst 11: A solution was prepared by mixing 12.10 g neattriethylaluminum (TEA), 9.38 g neat diethylaluminum chloride (DEAC) and20.02 g ethylbenzene. Two aliquots were added to this solution. Thefirst contained 2.3 g chromium (III) 2-ethylhexanoate, 1.14 gethylbenzene and 2.74 g 2,5-dimethylpyrrole. The second contained 2.3 gchromium (III) 2-ethylhexanoate and 1.14 g ethylbenzene. Ethylbenzenewas added to obtain a total volume of 100 mL. The catalyst prepared bythis method was tested in a 1 L continuous reactor. The average resultsof three test runs are shown in Table 3.

TABLE 3 Selectivity Purity Catalyst Productivity Catalyst (1-C₆═)(1-C₆═/C₆) (g 1-C₆═/g Cr) 11 91.2% 99.2% 80,759

The example shows high selectivity (91.2%), high purity (99.2%), andgood catalyst productivity (80,759 g 1−C₆=/g Cr) for the catalystpreparation.

Example 4

Catalyst 12: Ethylbenzene (10.67 g) was added to a dry 100 mL volumetricflask. Individual chemicals were added to each of four separate 20 mLsyringes. The chemicals added were 4.76 g chromium (III)2-ethylhexanoate dissolved in 2.38 g ethylbenzene, 12.06 g neattriethylaluminum (TEA), 9.26 g neat diethylaluminum chloride (DEAC) and2.74 g 2,5-dimethylpyrrole. To each of these syringes was addedsufficient ethylbenzene to provide a total volume of 19-20 mL. Theneedles of the syringes were added to the 100 mL volumetric flask andthe syringes emptied into the flask simultaneously at the same rate over30 minutes. After the additions were complete, ethylbenzene was added tothe flask to obtain a total volume of 100 mL. The catalyst (1 mL)prepared by this method was tested in a 1 L batch reactor at 116° C. and680 psig. The results of this test are shown in Table 4.

TABLE 4 Selectivity Purity Catalyst Productivity Catalyst (1-C₆═)(1-C₆═/C₆) (g 1-C₆═/g Cr) 12 92.0% 98.7% 34,325

Example 5

Catalyst 13-15: Catalyst was prepared by adding 15.85 g ethylbenzene toa dry 100 mL volumetric flask. To this flask was added 12.09 g neattriethylaluminum (TEA), 9.26 g neat diethylaluminum chloride (DEAC) and2.74 g 2,5-dimethylpyrrole. To this mixture was added 4.76 g chromium(III) 2-ethylhexanoate dissolved in 2.38 g ethylbenzene. The volume wasbrought to 100 mL with ethylbenzene. Different preparations of chromium(III) 2-ethylhexanoate were used to prepare the catalysts 13-15. Incatalyst 13 the chromium content of the chromium (III) 2-ethylhexanoatewas 10.5%. Infrared analysis and a methanol solubility test indicatedthat some water of hydration was present but no chromium oligomers. Incatalyst 14 the chromium content was 10.9% and infrared analysis andmethanol solubility indicated that neither water of hydration norchromium oligomers were present. In catalyst 15 the analysis indicatedthe presence of chromium oligomers. The catalysts prepared were testedfor activity in the continuous reactor (1 L) and the average results fortwo test runs of each preparation are shown in Table 5.

TABLE 5 Selectivity Purity Conversion Catalyst Productivity Catalyst(1-C₆═) (1-C₆═/C₆) (C₂═) (g 1-C₆═/g Cr) 13 90.3% 99.1% 79.0% 83,642 1488.7% 99.1% 84.5% 87,882 15 87.4% 98.1% 86.4% 88,460

The examples show that the best combination of purity and productivityare obtained when the water of hydration and chromium oligomers are notcontained in the chromium (III) 2-ethylhexanoate in significant amounts.

Example 6

Catalyst 16: Ethylbenzene (20.01 g) was added to a dry 125 mL Erlenmeyerflask equipped with a magnetic stirrer. To the ethylbenzene was added12.07 g neat triethylaluminum and 9.27 g neat diethylaluminum chloride.Into a 10 mL syringe was added 4.61 g chromium (III) 2-ethylhexanoatedissolved in 2.28 g ethylbenzene. Into a separate 10 mL syringe wasadded 2.73 g 2,5-dimethylpyrrole and 3.38 g ethylbenzene. Both of thesyringes had an approximate volume of 7.5 mL. The syringe needles wereput into opposite sides of the Erlenmeyer flask containing the dilutedaluminum alkyls and the contents were added simultaneously over 30minutes. After the addition was complete, the contents were transferredto a 100 mL volumetric flask and diluted to about 103 mL withethylbenzene. This catalyst was tested in a continuous 1 L reactor andthe results (average of three test runs) are shown in Table 6.

TABLE 6 Selectivity Purity Conversion Catalyst Productivity Catalyst(1-C₆═) (1-C₆═/C₆) (C₂═) (g 1-C₆═/g Cr) 16 93.0% 98.9% 66.6% 72,691

Example 7

Catalyst 17: Neat triethylaluminum (TEA, 0.27 g) was added to 30.01 g ofethylbenzene. This solution was added slowly to 4.62 g chromium (III)2-ethylhexanoate dissolved in 2.27 g ethylbenzene. This is an amount ofTEA sufficient to react with water and excess acid present in thechromium (III) 2-ethylhexanoate. The chromium solution, after reactionwith TEA, was added, over 50 minutes, to a solution containing TEA(11.81 g), diethylaluminum chloride (DEAC, 9.27 g), 2,5-dimethylpyrrole(2.75 g) and ethylbenzene (25.01 g). Ethylbenzene was subsequently addedto provide a total volume of 100 mL.

Catalyst 18: A comparison catalyst was prepared by adding 30.02 g ofethylbenzene to 4.62 g chromium (III) 2-ethylhexanoate dissolved in 2.27g ethylbenzene. The chromium solution was added, over 50 minutes, to asolution containing TEA (12.08 g), diethylaluminum chloride (DEAC, 9.28g), 2,5-dimethylpyrrole (2.74 g) and ethylbenzene (25.00 g).Ethylbenzene was subsequently added to provide a total volume of 100 mL.

These catalysts were tested for productivity in a 1 L continuousreactor. The average of two separate runs for each catalyst is shown inTable 7.

TABLE 7 Selectivity Purity Conversion Catalyst Productivity Catalyst(1-C₆═) (1-C₆═/C₆) (C₂═) (g 1-C₆═/g Cr) 17 90.0% 98.8% 88.3% 93,129 1889.1% 98.8% 82.7% 86,306

The addition of TEA to a chromium (III) 2-ethylhexanoate solutionprovided a catalyst with increased activity. It will also reducecorrosion in equipment after the catalyst has been inactivated. Theexample further provides an example of TEA addition to chromium to abatewater, acidic protons, or both.

Example 8

Catalyst 19: Neat triethylaluminum (TEA, 0.43 g) was added to 2.01 g ofethylbenzene. This solution was added slowly to 4.62 g chromium (III)2-ethylhexanoate in 27.27 g ethylbenzene. This is a small excess of theamount of TEA sufficient to react with water and excess acid present inthe chromium (III) 2-ethylhexanoate. To this chromium/TEA solution wasadded 2.73 g of 2,5-dimethylpyrrole. The chromium/TEA/dimethylpyrrolesolution, was added, over 30-40 minutes, to a solution containing TEA(11.62 g), diethylaluminum chloride (DEAC, 9.25 g) and ethylbenzene(15.00 g). Ethylbenzene was then added to provide a total volume of 100mL.

Catalyst 20: A comparison catalyst was prepared by adding 2.74 g2,5-dimethylpyrrole to 4.61 g chromium (III) 2-ethylhexanoate dissolvedin 2.27 g ethylbenzene. An immediate reduction in the viscosity of thechromium solution was observed. This chromium solution was added, over30-40 minutes, to a solution containing TEA (12.08 g), diethylaluminumchloride (DEAC, 9.27 g) and ethylbenzene (20.00 g). Ethylbenzene wasthen added to provide a total volume of 100 mL.

These catalyst preparations were tested for productivity in a 1 Lcontinuous reactor. The average of three separate test runs for eachcatalyst is shown in Table 8.

TABLE 8 Selectivity Purity Conversion Catalyst Productivity Catalyst(1-C₆═) (1-C₆═/C₆) (C₂═) (g 1-C₆═/g Cr) 19 92.0% 98.9% 74.4% 80,252 2092.5% 99.1% 71.8% 77,877

The addition of TEA provided a catalyst with increased activity. It canalso reduce corrosion in downstream equipment after the catalyst isinactivated.

Example 9

Several catalysts, catalysts 21-23 were prepared in which the molarratio of the 2,5-dimethylpyrrole/chromium was varied during the additionto the solution of aluminum alkyls.

Catalyst 21: A chromium solution of 4.61 g chromium (III)2-ethylhexanoate dissolved in 2.27 g ethylbenzene was divided into fourequal portions of 1.72 g each. To each of these portions was added adifferent amount of 2,5-dimethylpyrrole. To the first was added 1.52 g2,5-dimethylpyrrole, to the second 0.84 g, to the third 0.27 g and tothe fourth 0.12 g. The chromium/2,5-dimethylpyrrole portions were thenadded sequentially to a solution containing 12.07 g neattriethylaluminum (TEA), 9.29 g neat diethylaluminum chloride (DEAC) and20.01 g ethylbenzene. The total addition time was approximately 50minutes. The resulting catalyst solution was diluted to 100 mL withethylbenzene. The results from testing of this catalyst, in a 1 Lcontinuous reactor, are shown as Catalyst 21 in Table 9 below. Theresults shown are the average of four separate test runs.

Catalyst 22: A chromium solution of 4.61 g chromium (III)2-ethylhexanoate dissolved in 2.27 g ethylbenzene was divided into fourportions. To each of these portions was added a different amount of2,5-dimethylpyrrole and a similar amount of ethylbenzene. The firstportion contained 0.69 g chromium solution, 1.50 g 2,5-dimethylpyrroleand 7.51 g ethylbenzene. The second contained 1.38 g chromium solution,0.81 g 2,5-dimethylpyrrole and 7.52 g ethylbenzene. The third portioncontained 2.06 g chromium solution, 0.27 g 2,5-dimethylpyrrole and 7.50g ethylbenzene. The fourth portion contained 2.75 g chromium solution,0.16 g 2,5-dimethylpyrrole and 7.51 g ethylbenzene. Thechromium/2,5-dimethylpyrrole/ethylbenzene portions were then addedsequentially to a solution containing 12.07 g neat triethylaluminum(TEA), 9.27 g neat diethylaluminum chloride (DEAC) and 25.01 gethylbenzene. The total addition time was approximately 60 minutes. Theresulting catalyst solution was then diluted to 100 mL withethylbenzene. The results from testing of this catalyst, in a 1 Lcontinuous reactor, are shown as Catalyst 22 in Table 9 below. Theresults shown are the average of two separate test runs.

Catalyst 23: A chromium solution of 4.61 g chromium (III)2-ethylhexanoate dissolved in 2.27 g ethylbenzene was divided into fourportions. To each of these portions was added a different amount of2,5-dimethylpyrrole and a similar amount of ethylbenzene. The firstportion contained 0.35 g chromium solution, 1.53 g 2,5-dimethylpyrroleand 7.51 g ethylbenzene. The second contained 0.69 g chromium solution,0.81 g 2,5-dimethylpyrrole and 7.49 g ethylbenzene. The third portioncontained 2.06 g chromium solution, 0.27 g 2,5-dimethylpyrrole and 7.51g ethylbenzene. The fourth portion contained 3.77 g chromium solution,0.15 g 2,5-dimethylpyrrole and 7.50 g ethylbenzene. Thechromium/2,5-dimethylpyrrole/ethylbenzene portions were then addedsequentially to a solution containing 12.09 g neat triethylaluminum(TEA), 9.26 g neat diethylaluminum chloride (DEAC) and 25.02 gethylbenzene. The total addition time was approximately 60 minutes. Theresulting catalyst solution was then diluted to 100 mL withethylbenzene. The results from testing of this catalyst, in a 1 Lcontinuous reactor, are shown as Catalyst 23 in Table 9 below. Theresults shown are the average of two separate test runs.

Example 10

Catalyst 24: To a dry, nitrogen purged 5 gallon reactor was added 14.6lbs of dry, nitrogen purged ethylbenzene. The reactor was purged withnitrogen and a mixture consisting of 1,592 g neat triethylaluminum (TEA)and 1,238 g neat diethylaluminum chloride (DEAC) was added to thereactor. The aluminum alkyl mix vessel was rinsed with 0.2 lbs ofethylbenzene and this rinse was added to the reactor. A chromiumsolution was prepared by adding 700 mL of ethylbenzene to 630.9 gchromium (III) 2-ethylhexanoate. The mixture was stirred until solutionwas obtained and was transferred to a 1 gallon cylinder followed by a 75mL ethylbenzene rinse. The cylinder, containing the chromium solution,was pressured and depressured several times with nitrogen.Chromium/2,5-dimethylpyrrole (DMP) mixtures were added to the reactor infour batches from a chromium/DMP mix tank. For the first batch 65 g ofchromium and 233 mL DMP were added to the mix tank and then this mixturewas added to the reactor in 31-52 g increments with stirring and coolingso the temperature did not exceed 22° C. For the second batch 130 g ofchromium and 97 mL DMP were added to the mix tank and then this mixturewas added to the reactor in 48-58 g increments with stirring and coolingso the temperature did not exceed 22° C. For the third batch 326 g ofchromium and 39 mL DMP were added to the mix tank and then this mixturewas added to the reactor in 48-54 g increments with stirring and coolingso the temperature did not exceed 22° C. For the fourth batch 789 g ofchromium and 20 mL DMP were added to the mix tank and then this mixturewas added to the reactor in 100-130 g increments with stirring andcooling so the temperature did not exceed 24° C. Ethylbenzene (1 lb) wasadded to the chromium solution cylinder and used to rinse thechromium/DMP mix tank. The ethylbenzene rinse was then added to thereactor. The reactor was stirred for an additional 30 minutes. Afterstanding overnight the catalyst solution was filtered, using a filter asdescribed above. The catalyst solution was tested for activity in a 1 Lcontinuous reactor. The results are shown as Catalyst 24 in Table 9below. The results shown are the average of two separate test runs.

Example 11

Catalyst 25: To a dry, nitrogen purged 5 gallon reactor was added 14.0lbs of dry, nitrogen purged ethylbenzene. The reactor was purged withnitrogen and a mixture consisting of 1,283 g neat triethylaluminum (TEA)and 990 g neat diethylaluminum chloride (DEAC) was added to the reactor.The aluminum alkyl mix vessel was rinsed with 0.2 lbs of ethylbenzeneand this rinse was added to the reactor. A chromium solution wasprepared by adding 700 mL of ethylbenzene to 630.9 g chromium (III)2-ethylhexanoate. The mixture was stirred until solution was obtainedand was transferred to a 1 gallon cylinder followed by a 75 mLethylbenzene rinse. The cylinder, containing the chromium solution, waspressured and depressured several times with nitrogen.Chromium/2,5-dimethylpyrrole (DMP) mixtures were added to the reactor infour batches from a chromium/DMP mix tank. For the first batch 52 g ofchromium and 187 mL DMP were added to the mix tank and then this mixturewas added to the reactor in 20-52 g increments with stirring and coolingso the temperature did not exceed 21° C. For the second batch 104 g ofchromium and 78 mL DMP were added to the mix tank and then this mixturewas added to the reactor in 40-50 g increments with stirring and coolingso the temperature did not exceed 22° C. For the third batch 261 g ofchromium and 31 mL DMP were added to the mix tank and then this mixturewas added to the reactor in 90-101 g increments with stirring andcooling so the temperature did not exceed 23° C. For the fourth batch625 g of chromium and 16 mL DMP were added to the mix tank and then thismixture was added to the reactor in 30-108 g increments with stirringand cooling so the temperature did not exceed 23° C.

To the TEA/DEAC mix vessel was added 327 g neat TEA and 256 g neat DEAC.To the chromium/DMP mix tank was added 261 g of the chromium solution.To a separate cylinder connected to the reactor was added 78 mL of DMP.The reactor pressure was increased with nitrogen and the valvesconnecting each of the above cylinders to the reactor were opened.Reducing the reactor pressure transferred the contents of each of thesevessels simultaneously to the reactor while the reactor was beingstirred and cooled. An increase of 1° C. (20° C. to21° C.) was observedin the reactor temperature upon addition of the catalyst components.

Ethylbenzene (0.4 lb) was added to the chromium solution cylinder andused to rinse the chromium/DMP mix tank. The ethylbenzene rinse was thenadded to the reactor. Ethylbenzene (0.5 lb) was added to the DMPcylinder. This rinse of the DMP cylinder was added to the reactor.Ethylbenzene (0.2 lb) was added to the aluminum alkyl mix vessel andthen pressured into the reactor. The reactor was stirred for anadditional 30 minutes. After standing overnight the catalyst solutionwas filtered, using a filter as described above. The catalyst solutionwas tested for activity in a 1 L continuous reactor. The results areshown as Catalyst 25 in Table 9. The results shown are the average ofthree separate test runs.

TABLE 9 Selectivity Purity Conversion Catalyst Productivity Catalyst(1-C₆═) (1-C₆═/C₆) (C₂═) (g 1-C₆═/g Cr) 21 92.6% 98.8% 75.1% 81,432 2291.2% 99.1% 77.6% 82,927 23 90.5% 99.1% 79.7% 84,536 24 91.0% 99.2%87.5% 93,397 25 90.9% 99.0% 86.6% 92,297

Catalysts 21-24 show that varying the chromium to pyrrole ratio in adecreasing manner produces a catalyst which has increased selectivity,product purity, and productivity. Catalyst 25 demonstrates the separatesimultaneous addition of catalyst components to a heel of activecatalyst.

Example 12

Two catalysts were prepared, catalyst 26 and catalyst 27, with theaddition of a nitrogen compound to the alkylaluminum compound tosolubilize products resulting from the reaction of water and aluminumalkyls.

Catalyst 26: To a dry 100 mL volumetric flask was added 25.01 gethylbenzene, 12.07 g neat triethylaluminum (TEA) and 9.27 g neatdiethylaluminum chloride (DEAC) and 0.34 g tributylamine. To this wasadded a solution containing 4.61 g chromium (III) 2-ethylhexanoate, 2.27g ethylbenzene and 2.74 g 2,5-dimethylpyrrole. Ethylbenzene was thenadded to provide a total volume of 100 mL. Upon standing overnight nofilm was observed in the neck of the flask and no precipitate wasobserved. When the amine was not added to the catalyst preparation afilm was observed upon standing overnight. A film was observed in theneck of the flask after standing for an additional 24 hours. Thiscatalyst was tested for activity in a 1 L continuous reactor. Theresults of two separate test runs are shown in Table 10 below asCatalyst 26.

Catalyst 27: To a dry 100 mL volumetric flask was added 25.01 gethylbenzene, 12.07 g neat triethylaluminum (TEA) and 9.27 g neatdiethylaluminum chloride (DEAC) and 0.34 g tributylamine. To this wasadded a solution containing 4.61 g chromium (III) 2-ethylhexanoate, 2.27g ethylbenzene, 2.74 g 2,5-dimethylpyrrole and 1.06 g tributylamine.Ethylbenzene was then added to provide a total volume of 100 mL. Uponstanding overnight no film was observed in the neck of the flask and noprecipitate was observed. When the amine was not added to the catalystpreparation a film was observed upon standing overnight. A film wasobserved in the neck of the flask after standing for an additional 24hours. This catalyst was tested for activity in a 1 L continuousreactor. The results of two separate test runs are shown in Table 10 asCatalyst 27.

TABLE 10 Selectivity Purity Conversion Catalyst Productivity Catalyst(1-C₆═) (1-C₆═/C₆) (C₂═) (g 1-C₆═/g Cr) 26 93.0% 99.2% 70.4% 76,697 2792.8% 99.2% 69.5% 75,574

The example shows that the addition of an amine to the alkylaluminumcompounds inhibits formation of detrimental precipitation from thecatalyst solution.

Example 13

Catalyst 28: Chromium (III) 2-ethylhexanoate (18.44 g) dissolved in 9.1g ethylbenzene produces a viscous solution. When 2,5-dimethylpyrrole(10.96 g) was added to this viscous solution a much thinner solutionresults. This thinner solution is much more adaptable to water removalby molecular sieves. Activated 3 A molecular sieves (15.05 g) were addedto the chromium/pyrrole/ethylbenzene solution and allowed to stand withperiodic shaking for 22 days before catalyst preparation. A solution wasprepared in a 100 mL volumetric flask consisting of ethylbenzene (25.00g), neat triethylaluminum (12.07 g) and neat diethylaluminum chloride(9.26 g). To this aluminum alkyl solution was added 9.62 g of the driedchromium/pyrrole/ethylbenzene solution and the resulting catalyst wasdiluted to 100 mL with additional ethylbenzene. After standing overnighta film was observed in the neck of the flask but no precipitate wasobserved in the flask. This catalyst was tested in a 1 L continuousreactor and an average of two separate test runs is shown in Table 11 asCatalyst 28. A control using undried chromium/pyrrole/ethylbenzenesolution was made at the same time. After standing overnight a film wasobserved in the neck of the flask and a precipitate was also observed.This catalyst was tested in a 1 L continuous reactor and an average oftwo separate test runs is shown in Table 11 as Catalyst 29.

TABLE 11 Selectivity Purity Conversion Catalyst Productivity Catalyst(1-C₆═) (1-C₆═/C₆) (C₂═) (g 1-C₆═/g Cr) 28 93.2% 99.4% 76.0% 83,056 2994.3% 99.3% 64.5% 71,312

In addition to the improved catalyst productivity as shown, reduceddownstream corrosion could be obtained using the dried catalystcomponents.

Example 14

Catalyst 30-31: Chromium (III) 2-ethylhexanoate (222.10 g) was added toa round bottom flask equipped with a Dean-Stark tube. Ethylbenzene(147.39 g) was added and the flask was heated to reflux the contents.Reflux was continued until water no longer accumulated in the Dean-Starktube. Ethylbenzene and water (27.13 g) were discarded from theDean-Stark tube. This chromium solution was used to make catalyst byadding it to a 100 mL volumetric flask containing ethylbenzene (16.73g), neat triethylaluminum (12.28 g), neat diethylaluminum chloride (9.26g) and 2,5-dimethylpyrrole (2.74 g). Ethylbenzene was subsequently addedto dilute the catalyst to a 100 mL volume. This catalyst was tested in a1 L continuous reactor. The results of the test (two catalystpreparations and three separate test runs) are shown in Table 12 asCatalyst 30. A control catalyst prepared similarly but with chromium(III) 2-ethylhexanoate that had not been azeotrope dried was used. Theresults of testing the undried preparation are shown as Catalyst 31 inTable 12.

TABLE 12 Selectivity Purity Conversion Catalyst Productivity Catalyst(1-C₆═) (1-C₆═/C₆) (C₂═) (g 1-C₆═/g Cr) 30 89.4% 98.7% 81.5% 84,462 3188.5% 98.8% 82.3% 85,400

The example shows that drying the chromium component by azeotropicdistillation prepares an effective catalyst and also will reduceequipment corrosion.

Example 15

An ethylene trimerization catalyst composition was prepared usingmethods known to those skilled in the art, placed in the catalyst feedtank (under inert conditions) of a continuous 1-hexene productionprocess, and aged for approximately 900 hours. The continuous 1-hexeneproduction process was then started using the aged catalyst in the feedtank for the trimerization of ethylene to 1-hexene. Periodically,additional fresh ethylene trimerization catalyst was prepared and addedto the catalyst used in the continuous 1-hexene production process. Theaverage age of the ethylene oligomerization catalyst compositionperiodically calculated to determine the average time the catalyst hadresided in the catalyst feed tank based upon the average catalystcomposition in the catalyst feed tank. Throughout the continuous1-hexene production process, samples of the continuous 1-hexeneproduction process product we removed and analyzed for 1-hexene content.FIG. 5 shows the impact of the average catalyst residence time (i.e.catalyst age) on the purity of the hexene production produced by thecontinuous 1-hexene production process. FIG. 5 indicates that the purityof the 1-hexene product is negatively impacted by increasing age of theethylene trimerization catalyst.

1. A method of making a catalyst for use in oligomerizing an olefincomprising a chromium-containing compound, a pyrrole-containingcompound, a metal alkyl, and a halide-containing compound, comprisingcontacting the chromium-containing compound, the pyrrole-containingcompound, the metal alkyl, or combinations thereof with a previouslyprepared oligomerization catalyst composition.
 2. The method of claim 1,wherein the chromium-containing compound, the pyrrole-containingcompound, the metal alkyl, and the halide-containing compound aresimultaneously contacted with a previously prepared oligomerizationcatalyst composition.
 3. The method of claim 1, further comprisingforming a pyrrole-chromium mixture by contacting the pyrrole-containingcompound and the chromium-containing compound.
 4. The method of claim 3,wherein the pyrrole-containing compound and the chromium-containingcompound are contacted at an about constant pyrrole:Cr molar ratio toform the pyrrole-chromium mixture.
 5. The method of claim 3, wherein thepyrrole-containing compound and the chromium-containing compound arecontacted at a variable pyrrole:Cr molar ratio to form thepyrrole-chromium mixture.
 6. The method of claim 1, further comprisingforming a pyrrole-metal alkyl mixture comprising contacting thepyrrole-containing compound with the metal alkyl.
 7. The method of claim1, wherein the chromium-containing compound and the pyrrole-containingcompound are contacted with the previously prepared oligomerizationcatalyst composition at a pyrrole:Cr molar ratio that is about constantover the period of time.
 8. The method of claim 1, wherein thechromium-containing compound and the pyrrole-containing compound arecontacted with the previously prepared oligomerization catalystcomposition at a pyrrole:Cr molar ratio that is about variable over theperiod of time.
 9. The method of claim 1, wherein the previouslyprepared oligomerization catalyst composition comprises the same ordifferent chromium-containing compound, pyrrole-containing compound,metal alkyl, and halide-containing compound.
 10. A method of making acatalyst for use in oligomerizing an olefin comprising achromium-containing compound, a pyrrole-containing compound, a metalalkyl, a halide-containing compound, and optionally a solvent, themethod comprising abating precipitate by contacting anitrogen-containing compound with a metal alkyl prior to contacting themetal alkyl with the chromium-containing compound, thepyrrole-containing compound, the non-metal halide-containing compound,the solvent, or combinations thereof.
 11. The method of claim 10,wherein the nitrogen-compound is selected from the group consisting ofamines, pyrroles, pyridines, substituted pyrroles such as indoles, diand tri nitrogen heterocycles, or combinations thereof.
 12. The methodof claim 10, wherein the nitrogen-containing compound comprises2,5-dimethylpyrrole.
 13. The method of claim 12, wherein thenitrogen-containing compound comprises tributyl amine.
 14. The method ofclaim 10, wherein the final catalyst product is comprised of from about0.001 to about 10 mole ratio of nitrogen to metal.
 15. A method ofmaking a catalyst for use in oligomerizing an olefin, comprising achromium-containing compound, a pyrrole-containing compound, a metalalkyl, a halide-containing compound, and optionally a solvent, themethod comprising: abating all or a portion of water, acidic protons, orboth from a composition comprising the chromium-containing compound, acomposition comprising the pyrrole-containing compound, a compositioncomprising a non-metal halide-containing compound, a compositioncomprising the solvent, or combinations thereof prior to contact thereofwith a composition comprising a metal halide-containing compound,wherein all or a portion of the water is removed from thechromium-containing compound prior to contact with the metalhalide-containing compound, and wherein the water is removed from thechromium-containing compound by contacting the chromium-containingcompound with a solvent to form a solution and the solution is subjectedto an azeotropic distillation.
 16. The method of claim 15, wherein thesolvent comprises an aromatic compound, a halogentated compound, aparaffin, or combinations thereof.
 17. The method of claim 16, whereinthe aromatic compound comprises benzene, toluene, ethylbenzene, mixedxylenes, ortho-xylene, meta-xylene, para-xylene, or combinationsthereof.
 18. The method of claim 15, wherein the amount of water removedis monitored by infrared analysis or other known methods used todetermine water content.
 19. A method of making a catalyst for use inoligomerizing an olefin comprising a chromium-containing compound, apyrrole-containing compound, a metal alkyl, a halide-containingcompound, and optionally a solvent, the method comprising simultaneouslycontacting a composition comprising the chromium-containing compound, acomposition comprising the pyrrole-containing compound, and acomposition comprising the metal alkyl.
 20. The method of claim 19further comprising simultaneously contacting a composition comprisingthe halide-containing compound with the composition comprising thechromium-containing compound, the composition comprising thepyrrole-containing compound, and the composition comprising the metalalkyl.